Visual Inspection of Tanks & Pressure Vessels [PDF]

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Yanbu Steel Company Quality Control Procedure TITLE

:

Standard Visual & Dimensional Testing Procedure

DOCUMENT NO :

VT-1

ISSUE NO.

:

1

COPY NO.

:

0

YSC hereby certifies that the above named procedure complies with the requirements of the latest edition of the respective Codes and Standards listed below when noted in the procedure.

CODES AND STANDARDS ASME B&PV Code Section V (2007 edition with 2008 & 2009 Addenda) ASME B&PV Code Section VIII Divisions 1 &2 (2007 edition with 2008 & 2009 Addenda) API 620 (11th Edition, Feb. 2008 with Addendum 1, Mar. 2009) API 650 (11th Edition, June 2007 with Addendum 1, Nov. 2008) ASME B31.1-2007 ASME B31.3-2008 ANSI/AWWA D100-05 ANSI/ASNT CP-189-2006

Prepared By:

Reviewed By:

Accepted by:

Malik Sajjad Akhtar ASNT NDT Level III Certificate # 153071

Ishfaq Ur Rehman ASNT NDT Level III Certificate # 165135

Iain M. Lemond QA/QC Manager Yanbu Steel Company

Rev. 2

Issued for implementation

YSC Level III

Date Mar. 23, 2010

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE Record of Change Revision 2

March 23, 2010

Location

Action

Description

Page 1

Modification

Added latest addenda and deleted ASNT SNT-TC-1A

Page 4

Modification

Deleted ASNT SNT-TC-1A and added ANSI/ASNT CP-189-2006

Revision 1

August 17, 2009

Location

Action

Page 2

Addition

Record of Change

Page 3

Addition

Table of Contents

Section 1.4

Modification

Section 3

Addition

Added Definitions of direct and remote visual testing

Section 4.3

Addition

Added requirements for visual examination personnel and addresses welding inspection, tanks, piping and tanks certification exemption

Section 10

Modification

Section 10.1 To Section 10.8

Addition

Revision 0 Location

Description

Appendices numerical order modified

Numerical Order modified as per section 1.4 Incorporated dimensional requirements along with visual inspection criteria in accordance with the latest revisions of applicable codes and standards as described on cover page.

February 01, 2003 Action

Description Initial Publish

Doc Ref: VT-1 – Rev. 2

Page 2 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE TABLE OF CONTENTS 1

Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

2

Governing Documents . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

3

Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

4

Personnel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

5

General Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

6

Equipments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

7

Examination Technique . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

8

Records . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

9

Acceptance Standards, Repairs & Retests . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

10

Appendices

Appendix 1 - ASME Section VIII Division 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . 6 Appendix 2 - ASME Section VIII Division 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Appendix 3 - API Standard 620 Design and Construction of Large, Welded, Low Pressure Storage Tanks . . . . . . . 13 Appendix 4 - API Standard 650 Welded Steel Tanks for Oil . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Appendix 5 - AWS D1.1 Structural Welding Code - Steel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Appendix 6 - ASME B31.1 Pressure Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Appendix 7 - ASME B31.3 Process Piping . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 Appendix 8 - ANSI/AWWA D100 Welded Carbon Steel Tanks for Water Storage . . . . . . . . . . . . . . . . . . . . . . 26

Doc Ref: VT-1 – Rev. 2

Page 3 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 1.0

SCOPE

1.1

This procedure specifies the technique, acceptance standards and documentation requirements for all visual examinations.

1.2

Visual examination is generally used to determine the acceptability of such things as the surface condition of the part, alignment of mating surfaces as well as size, shape and condition of welds.

1.3

There may specific contract requirements which are more stringent than or in addition to the requirements of this procedure. These requirements shall be specified on the detail or erection drawings.

1.4

Section 10 contains appendices, as listed below, covering the detail of acceptance standards, repairs and retests for the applicable CODE or STANDARD. Appendices 1 through 8 are at the end of the procedure. When this procedure is distributed to the field and customer for a contract, the main document and only the applicable Appendix (ces) needed are to be issued. Section 10.1

Appendix 1 – ASME Section VIII Division 1

Section 10.2

Appendix 2 – ASME Section VIII Division 2

Section 10.3

Appendix 3 – API 620

Section 10.4

Appendix 4 – API 650

Section 10.5

Appendix 5 – AWS D1.1

Section 10.6

Appendix 6 – ASME B31.1

Section 10.7

Appendix 7 – ASME B31.3

Section 10.8

Appendix 8 – ANSI/AWWA D100

2.0

GOVERNING DOCUMENTS

2.1

Codes and Standards Those referenced in the Contract Documents

2.2

YSC Documents Drawings and Procedures as listed on the Contract Drawing Index.

3.0

DEFINITIONS

3.1

Direct Visual Testing Visual testing where there is an uninterrupted optical path from the observer’s eye to the test area. This is either unaided or aided via e.g. mirror, lens, endoscope or fibre optic.

3.2

Remote Visual Testing Visual testing where is an interrupted optical path from the observer’s eye to the test area. Remote visual testing may cover the use of photography, video systems and robots.

4.0

PERSONNEL

4.1

Visual examination personnel shall have vision, with correction if necessary, to enable them to read a Jaeger Type No.1 standard chart at a distance of not less than 12 inches (305 mm). This requirement shall be checked annually.

4.2

Visual examination personnel shall be qualified and certified in accordance with YSC Quality Control Procedure “Certification Procedure for Qualification and Certification of Nondestructive Testing Personnel” in accordance with either ASNT Standard for Certification and Qualification of Nondestructive Testing Personnel (ANSI/ASNT CP-189) or as per client requirements.

4.3

Personnel shall be competent in the techniques of visual examination, including the examination, evaluation and interpretation of the results, except that where the examination method consists of more than one operation, personnel may be certified as being competent only for one or more of these operation. Those who possess certification on weld inspection, tanks, piping or pressure vessels inspection (CWI, CSWIP, API 510, API 570 and/or API 653) shall be exempted from above requirement.

4.3

For ASME B31.1 work, visual examination personnel shall be qualified and certified in accordance with the requirements of paragraph 136.1 of ASME B31.1.

Doc Ref: VT-1 – Rev. 2

Page 4 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 5.0

GENERAL REQUIREMENTS

5.1

Extent of Examination

5.1.1

Items to be examined in accordance with this procedure shall be as specified on the detail fabrication and erection drawings and applicable procedures and specifications for the contract.

5.1.2

This includes: assuring proper materials are used; inspecting joint fit-up, alignment and tack welds; assuring that welding procedures, which are specified on the drawings are used; assuring that no unspecified welds are added without approval; inspecting final weld shape, size and condition; inspecting welds after PWHT; inspection during NDT (PT, MT) and inspection during hydrotest / pressure test.

5.2

Surface Preparation

5.2.1

Slag, oil, dirt, moisture, grease, and other foreign matter that would interfere with the examination shall be removed from the area of interest and for a distance of at least one (1) inch (25.4 mm) from the area of interest prior to any visual examination.

5.2.2

In general, welds shall be visually inspected after the completed welds have cooled to ambient temperature.

6.0

EQUIPMENT Artificial Light Source Mirrors Magnifiers Straight Edges or Rules Weld Gauges

7.0

EXAMINATION TECHNIQUE

7.1

Direct Visual Examination Direct visual examination may usually be made when access is sufficient to place the eye within 24 in. (600 mm) of the surface to be examined and at an angle not less than 30 deg to the surface to be examined. Mirrors may be used to improve the angle of vision, and aids such as a magnifying lens may be used to assist examinations. Illumination (natural or supplemental white light) for the specific part, component, vessel, or section thereof being examined is required. The minimum light intensity at the examination surface/site shall be 100 footcandles (1000 lux). The light source, technique used, and light level verification is required to be demonstrated one time, documented, and maintained on file.

7.2

Remote Visual Examination In some cases, remote visual examination may have to be substituted for direct examination. Remote visual examination may use visual aids such as mirrors, telescopes, borescopes, fiber optics, cameras, or other suitable instruments. Such systems shall have a resolution capability at least equivalent to that obtainable by direct visual observation.

8.0

RECORDS When required by contract or the applicable Code or Standard, acceptable visual inspections shall be recorded on the Process Control Plan or VT Inspection Report Form 18077, as they apply. The sign-off shall include any special equipment used to complete the visual inspection.

9.0

ACCEPTANCE STANDARDS, REPAIRS AND RETESTS

9.1

All materials, joint preparation, assembly and welding shall be in accordance with the applicable contract drawings, procedures and specifications.

9.2

Repairs and Retests Unacceptable conditions found during inspections shall be marked on the item, corrected using qualified welding procedures, welders and welding operators, and re-inspected using the original inspection procedure for acceptance.

Doc Ref: VT-1 – Rev. 2

Page 5 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.1

Appendix 1 – ASME Section VIII Division 1 Rules for Construction of Pressure Vessels

10.1.1

Weld which contain cracks and unacceptable.

10.1.2

Welded joints shall have complete penetration and full fusion. As-welded surfaces are permitted; however, the surface of welds shall be sufficiently free from coarse ripples, grooves, overlaps, and abrupt ridges and valleys to permit proper interpretation of radiographic and other required nondestructive examinations. If there is a question regarding the surface condition of the weld when interpreting a radiographic film, the film shall be compared to the actual weld surface for determination of acceptability.

10.1.3

A reduction in thickness due to the welding process is acceptable provided all of the following conditions are met: a.

The reduction in thickness shall not reduce the material of the adjoining surfaces below the minimum required thickness at any point.

b.

The reduction in thickness shall not exceed 1⁄32 in. (1 mm) or 10% of the nominal thickness of the adjoining surface, whichever is less.

Note:

It is not the intent of this paragraph to require measurement of reductions in thickness due to the welding process. If a disagreement between the Manufacturer and the Inspector exists as to the acceptability of any reduction in thickness, the depth shall be verified by actual measurement.

10.1.4

If 100% radiography does not apply, rounded indications on the surface of welds shall not be cause for rejection; however, for guidance purposes only, an acceptable surface condition of a weld may be judged on the basis of founded indications as contained in Section VIII, Division 1 (Appendix 4)

10.1.5

Weld Reinforcement When a single-welded butt joint is made by using a backing strip which is left in place, the requirement for reinforcement applies only to the side opposite the backing strip. To assure that the weld grooves are completely filled so that the surface of the weld metal at any point does not fall below the surface of the adjoining base materials, weld metal may be added as reinforcement on each face of the weld. The thickness of the weld reinforcement on each face shall not exceed the following: Customary Units Maximum Reinforcement, in. Material Nominal Thickness, in. Less than ⁄32 3 3 ⁄32 to ⁄16, incl. 3 1 Over ⁄16 to ⁄2, incl. 1 Over ⁄2 to 1, incl. Over 1 to 2, incl. Over 2 to 3, incl. Over 3 to 4, incl. Over 4 to 5, incl. Over 5 3

Category B & C Butt Welds

Other Welds

⁄32 1 ⁄8 5 ⁄32 3 ⁄16 1 ⁄4 1 ⁄4 1 ⁄4 1 ⁄4 5 ⁄16

⁄32 ⁄16 3 ⁄32 3 ⁄32 1 ⁄8 5 ⁄32 7 ⁄32 1 ⁄4 5 ⁄16

3

1 1

SI Units Maximum Reinforcement, mm. Material Nominal Thickness, mm Less than 2.4 2.4 to 4.8, incl. Over 4.8 to 13, incl. Over 13 to 25, incl. Over 25 to 51, incl. Over 51 to 76, incl. Over 76 to 102, incl. Over 102 to 127, incl. Over 127

Doc Ref: VT-1 – Rev. 2

Category B & C Butt Welds

Other Welds

2.4 3.2 4.0 4.8 5 6 6 6 8

0.8 1.6 2.4 2.4 3.2 4 6 6 8

Page 6 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.1.6

Concavity Concavity due to the welding process on the root side of a single welded circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinner member of the two sections being joined and the contour of the concavity is smooth.

10.1.7

Alignment Tolerance a.

Alignment of sections at edges to be butt welded shall be such that the maximum offset is not greater than the applicable amount for the welded joint category under consideration, as listed in Table UW-33. The section thickness t is the nominal thickness of the thinner section at the joint.

b.

Any offset within the allowable tolerance provided above shall be faired at a three to one taper over the width of the finished weld, or if necessary, by adding additional weld metal beyond what would otherwise be the edge of the weld. TABLE UW - 33 Customary Units Joint Categories

Section Thickness, in.

A

Up to ⁄2, incl.

B, C, & D

⁄4 t

1

⁄4 t

Over ⁄2 to ⁄4, incl.

1

⁄8 in.

1

⁄4 t

Over ⁄4 to 1 ⁄2, incl.

1

⁄8 in.

Over 1 ⁄2 to 2, incl.

1

⁄8 in.

1

1

3

3

1

1

1

3

1

⁄8 t 1

1

Lesser of ⁄16 t or ⁄8 in.

Over 2

⁄16 in.

3

Lesser of ⁄8 t or ⁄4 in. 3

SI Units Joint Categories

Section Thickness, mm

A

B, C, & D

⁄4 t

1

⁄4 t

Over 13 to 19, incl.

3 mm

1

⁄4 t

Over 19 to 38, incl.

3 mm

Over 38 to 51, incl.

3 mm

Up to 13, incl.

Over 51

1

Lesser of ⁄16 t or 10 mm 1

5 mm 1

⁄8 t

Lesser of ⁄8 t or 19 mm 1

FIG. UW-3 ILLUSTRATION OF WELDED JOINT LOCATIONS TYPICAL OF CATEGORIES A, B, C, AND D

10.1.8

Out – of – Roundness of Cylindrical, Conical, and Spherical Shells subjected to Internal Pressure The shell of a completed vessel shall be substantially round and shall meet the following requirements: a.

The difference between the maximum and minimum inside diameters at any cross section shall not exceed 1% of the nominal diameter at the cross section under consideration. The diameters may be measured on the inside or outside of the vessel. If measured on the outside, the diameters shall be corrected for the plate thickness at the cross section under consideration (see Fig. UG-80.2).

Doc Ref: VT-1 – Rev. 2

Page 7 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE b.

When the cross section passes through an opening or within 1 I.D. of the opening measured from the center of the opening, the permissible difference in inside diameters given above may be increased by 2% of the inside diameter of the opening. When the cross section passes through any other location normal to the axis of the vessel, including head-to-shell junctions, the difference in diameters shall not exceed 1%.

For vessels with longitudinal lap joints, the permissible difference in inside diameters may be increased by the nominal plate thickness. FIGURE UG-80.2 Examples of Differences between Maximum and Minimum Inside Diameters in Cylindrical, Conical, and Spherical Shells

10.1.9

Tolerance for Formed Heads A

The inner surface of a torispherical, toriconical, hemispherical, or ellipsoidal head shall not deviate outside of the specified shape by more than 11⁄4% of D nor inside the specified shape by more than 5⁄8% of D, where D is the nominal inside diameter of the vessel shell at point of attachment. Such deviations shall be measured perpendicular to the specified shape and shall not be abrupt. The knuckle radius shall not be less than that specified.

B

Hemispherical heads or any spherical portion of a torispherical or ellipsoidal head designed for external pressure shall, in addition to satisfying (a) above, meet the tolerances specified for spheres in UG-80(b) using a value of 0.5 for L/Do.

C

Measurements for determining the deviations shall be taken from the surface of the base metal and not from welds.

D

The skirts of heads shall be sufficiently true to round so that the difference between the maximum and minimum inside diameters shall not exceed 1% of the nominal diameter.

E

When the skirt of any unstayed formed head is machined to make a driving fit into or over a shell, the thickness shall not be reduced to less than 90% of that required for a blank head or the thickness of the shell at the point of attachment. When so machined, the transition from the machined thickness to the original thickness of the head shall not be abrupt but shall be tapered for a distance of at least three times the difference between the thicknesses.

Doc Ref: VT-1 – Rev. 2

Page 8 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.2

Appendix 2 – ASME Section VIII Division 2 Alternative Rules – Rules for Construction of Pressure Vessels All welds for pressure retaining parts shall be visually examined. Welds that are observed to have indications exceeding the criteria given in Table 7.6 are unacceptable. Unacceptable indications shall be removed or reduced to an indication of acceptable size. Whenever an indication is removed by chipping or grinding and subsequent repair by welding is not required, the area shall be blended into the surrounding surface so as to avoid notches, crevices, or corners.

Table 7.6 – Visual Examination Acceptance Criteria No. 1

Acceptance Criteria

Type of Imperfection Cracks (all)

---

Not permitted

Gas cavity (all) 2

Not Permitted Shrinkage cavity (all)

3

Slag Inclusions (all) Flux inclusions (all) Oxide inclusions (all) Metallic inclusions (all)

4

Incomplete fusion (all)

Not permitted.

5

Lack of penetration

Not permitted if a complete penetration weld is required

---

Not permitted when occurring at the surface 2.

The reduction in thickness shall not reduce the material of the adjoining surfaces below the minimum required thickness at any point. 6

Undercut

The reduction in thickness shall not exceed 0.8 mm (1/32 in.) or 10% of the nominal thickness of the adjoining surface, whichever is less. Acceptable weld reinforcement in butt welding joints shall be in accordance with Table 6.6. A smooth transition is required. Table 6.6 – Maximum Reinforcement for Welded Joints Circumferential Joints in Piping and Tubing

Other Welds

2.5 mm (3 / 32 in) < t

2.5 mm (3/32 in.)

0.8 mm (1/32 in.)

2.5 mm (3 / 32 in) ≤ t < 5mm (3 /16 in)

2.5 mm (3/32 in.)

1.5 mm (1/16 in.)

5 mm (3 /16 in) ≤ t < 13 mm (1/ 2 in)

3 mm (1/8 in.)

2.5 mm (3/32 in.)

13 mm (1/ 2 in) ≤ t < 25 mm (1in)

4.0 mm (5/32 in.)

2.5 mm (3/32 in.)

25 mm (1in) ≤ t < 50 mm (2 in)

4.0 mm (5/32 in.)

3 mm (1/8 in.)

50 mm (2 in) ≤ t < 76 mm (3 in)

4.0 mm (5/32 in.)

4.0 mm (5/32 in.)

76 mm (3 in) ≤ t < 100 mm (4 in)

5.5 mm (7/32 in.)

5.5 mm (7/32 in.)

100 mm (4 in) ≤ t < 125 mm (5 in)

6 mm (1/4 in.)

6 mm (1/4 in.)

t≥125mm(5in)

8 mm (5/16 in.)

8 mm (5/16 in.)

Section Thickness

7

Weld reinforcement

Notes: t is the nominal thickness of the thinner section at the weld joint.

Doc Ref: VT-1 – Rev. 2

Page 9 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE Type of Imperfection

No.

Acceptance Criteria Alignment of sections at edges to be butt welded shall be such that the maximum offset is not greater than shown below (a, b & c). a)

Cylindrical Shells The maximum allowable offset in welded joints in cylindrical shells shall be as given in Table 6.4.

b)

Spherical Shells and for Hemispherical Heads Welded to Cylindrical Shells Joints in spherical vessels, joints within heads, and joints between cylindrical shells and hemispherical heads shall meet the requirements in Table 6.4. Table 6.4 – Maximum Allowable Offset In Welded Joints Section Thickness

Category A Joints

Category B, C, D Joints

13 mm (1/ 2 in) ≤ t

t /4

t /4

13 mm (1/ 2 in) < t ≤ 19 mm (3 / 4 in)

3 mm (1/8 in)

t /4

19 mm (3 / 4 in) < t ≤ 38 mm (1−1/ 2 in)

3 mm (1/8 in)

5 mm (3/16 in)

38 mm (1−1/ 2 in) < t ≤ 50 mm (2 in)

3 mm (1/8 in)

t /8

t > 50 mm (2in)

Max [t / 16, 10 mm (3 /8 in)]

Max [t /8, 19 mm (3 / 4 in)]

Notes: t is the nominal thickness of the thinner section at the weld joint.

c) 8

Joint offset

---

Alignment tolerances at edges to be butt welded for quenched and tempered high strength steels shall be: Longitudinal Joint Alignment Misalignment shall not exceed 20% of the nominal plate thickness or 2.5 mm (3/32 in.). Circumferential Joint Alignment Misalignment shall not exceed the following values: i) If t ≤ 24 mm (15/16 in.), then the tolerance is 20% of the plate thickness. ii) If 24 mm (15/16 in.) < t ≤ 38 mm (1-1/2 in.), then the tolerance is 5 mm (3/16 in.). ii) If t > 38 mm (1-1/2 in.), then the tolerance is 12.5% of the nominal plate thickness but not more than 6 mm (1/4 in.)

Fairing of Offsets within Allowable Tolerances Any offset within the allowable tolerance provided above shall be faired at a 3:1 taper over the width of the finished weld or, if necessary, by adding additional weld metal beyond what would have been the edge of the weld. Alternatively, offsets greater than those permitted are allowable provided that the maximum offset is acceptable to the Inspector prior to welding and if agreed to by the user, the assessment procedures in Part 5 or in API 579-1/ASME FFS-1 may be used to qualify the design of components that have shell tolerances that do not satisfy the fabrication tolerances as stated above. If API 579-1/ASME FFS-1 is used in the assessment, a Remaining Strength Factor of 0.95 shall be used in the calculations unless another value is agreed to by the user. However, the Remaining Strength Factor shall not be less than 0.90. In addition, a fatigue analysis shall be performed in accordance with API 579-1/ASME FFS-1 as applicable.

Doc Ref: VT-1 – Rev. 2

Page 10 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE If a fatigue analysis is required, then the peaking height, dp , at Category A weld joints shall be measured by either an inside or outside template, as appropriate (see Figure 6.1).

9

Peaking

---

(a) (b) Figure 6.1 – Peaking Height at a Category A Joint

The chord length of the template shall be the larger of D/ 6 or 300 mm (12 in.), but need not exceed 900 mm (36 in.). If the weld joint is in a torispherical or an ellipsoidal head, the inside diameter, D, shall be equal to the diameter of the spherical portion of the head. If the weld joint is in a 2:1 ellipsoidal head, D shall be equal to 1.8 times the nominal inside diameter of the attached cylindrical shell. 10

Stray flash or arc strike

---

Not permitted2

11

Spatter

---

Spatter shall be minimized2.

---

Not permitted2.

Torn surface 12

Grinding mark Chipping mark

13

Concavity due to the welding process on the root side of a single welded circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinner member of the two sections being joined and the contour of the concavity is smooth.

Concavity

Notes: 1)

The following symbols are used in this table: a. Nominal fillet weld throat thickness b. Width of weld reinforcement d. Diameter of pore h. Height of imperfections t. Wall or Plate thickness

2)

These imperfections may be removed by blend grinding

Figure 4.2.1 – Weld Joint Locations Typical of Categories A, B, C, D and E

Doc Ref: VT-1 – Rev. 2

Page 11 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.2.1

Shell Tolerances The shell of a completed vessel shall satisfy the following requirements.

10.2.2

a)

The difference between the maximum and minimum inside diameters at any cross section shall not exceed 1% of the nominal diameter at the cross section under consideration. The diameters may be measured on the inside or outside of the vessel. If measured on the outside, the diameters shall be corrected for the plate thickness at the cross section under consideration.

b)

When the cross section passes through an opening or within one inside diameter of the opening measured from the center of the opening, the permissible difference in inside diameters given above may be increased by 2% of the inside diameter of the opening. When the cross section passes through any other location normal to the axis of the vessel, including head-to-shell junctions, the difference in diameters shall not exceed 1%.

Head Tolerances Tolerances for formed heads shall satisfy the following requirements. a)

The inner surface of torispherical, toriconical, hemispherical, or ellipsoidal heads shall not deviate outside of the specified shape by more than 1.25% of D nor inside the specified shape by more than 0.625% of D, where D is the nominal inside diameter of the vessel shell at the point of attachment. Such deviations shall be measured perpendicular to the specified shape and shall not be abrupt. The knuckle radius shall not be less than that specified

b)

Measurements for determining the deviations specified shall be taken from the surface of the base metal and not from welds.

c)

When the straight flange of any unstayed formed head is machined to make a lap joint connection to a shell, the thickness shall not be reduced to less than 90% of that required for a blank head or the thickness of the shell at the point of attachment. When so machined, the transition from the machined thickness to the original thickness of the head shall not be abrupt but shall be tapered for a distance of at least three times the difference between the thicknesses.

Doc Ref: VT-1 – Rev. 2

Page 12 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.3

Appendix 3 – API 620 Design and Construction of Large, Welded, Low-pressure Storage Tanks A weld shall be acceptable by visual examination if examination shows the following:

10.3.1

The weld has no crater cracks or other surface cracks.

10.3.2

The edges of the weld shall merge smoothly with the surface of the plate without a sharp angle. Maximum permissible weld undercut is 1/64 in. for longitudinal or meridional butt joints, similarly oriented permanent attachments, attachment welds for nozzles, manholes, flush-type openings, and the inside shell-to-flat bottom welds. For circumferential and latitudinal butt joints, similarly oriented permanent attachments, and annular ring butt joints, the maximum permissible undercutting is 1/32 in.

10.3.3

The frequency of surface porosity in welds does not exceed one cluster (one or more pores) in each 4 in. of length, and the maximum diameter of each cluster does not exceed 3/32 in.

10.3.4

Complete fusion and required penetration exists at the joint between the weld metal and the base metal.

10.3.5

Aligning of Main Joints Particular care shall be taken in matching up the edges of all plates within the tolerances of offset as follows:

10.3.6

a.

For plates 1/4 in. in thickness and less, 1/16 in.

b.

For plates over 1/4 in. in thickness, 25% of the plate thickness or 1/8 in., whichever is smaller.

Matching Plates of Unequal Thickness For plates over 1/2-in. thick in the sidewalls, roof, or bottom of a tank, if the thickness of two adjacent plates that are to be butt-welded together differ by more than 1/8 in., the thicker plate shall be trimmed to a smooth taper that extends for a distance at least four times the offset between the abutting surfaces so that the adjoining edges will be of approximately the same thickness.

10.3.7

10.3.8

Plumbness a.

For cylindrical sidewalls, the maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/200 of the total tank height.

b.

The out-of-plumbness in one shell plate shall not exceed the permissible variations for flatness and waviness specified in ASTM A6 or ASTM A20, whichever is applicable for carbon and alloy steels. For stainless steels, ASTM A480 is applicable. For aluminum plates, Table 5.13 of ANSI H35.2 provides the dimensional flatness tolerance.

Roundness a.

For cylindrical sidewalls, the horizontal circular cross section of a large, low pressure storage tank shall be sufficiently true to round so that the difference between the maximum and minimum diameters (measured inside or outside) at any section in a cylindrical wall shall not exceed 1% of the average diameter or 12 in., whichever is less, except as modified for flat-bottom tanks for which the radii measured at 1 ft 0 in. above the bottom corner weld shall not exceed the tolerances listed in Table 6-1.

b.

The skirts or cylindrical ends of formed tops or bottoms shall be sufficiently true to round so that the difference between the maximum and minimum diameters shall not exceed 1% of the nominal diameter. Table 6-1—Diameter Range Versus Radius Tolerance

10.3.9

Diameter Range (ft)

Radius Tolerance (in.)

< 40

± /2

40 to < 150

± /4

150 to < 250

±1

≥ 250

± 1 /4

1 3

1

Local Deviations Local deviations from the theoretical shape, such as weld discontinuities and flat spots, shall be limited as follows: a.

Using a horizontal sweep board 36-in. long, peaking at vertical joints shall not exceed 1/2 in. This may be increased to 1 in. for aluminum shells (see Appendix Q).

Doc Ref: VT-1 – Rev. 2

Page 13 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE b.

Using a vertical sweep board 36-in. long, banding at horizontal joints shall not exceed 1/2 in. This may be increased to 1 in. for aluminum shells (see Appendix Q).

c.

Flat spots in the vertical plane shall not exceed the appropriate plate flatness and waviness requirements of 10.3.7

10.3.10 Fitting Attachments All lugs, brackets, nozzles, manhole frames, reinforcement around openings, and other appurtenances shall fit and conform to the curvature of the surface to which they are attached. 10.3.11 Reinforcement shall not exceed the following: Table 6-3 — Maximum Thickness of Reinforcement on Welds Plate Thickness (in.)

Maximum Thickness of Reinforcement (in.)

≤½

1

> ½ thru 1

3

>1

/8

/16

¼

10.3.12 Reinforcement of butt welded areas that are to be radiographed shall be further limited to the following: Table 7-1 — Maximum Thickness of Reinforcement on Welds for Radiography Examined Joints Plate Thickness (in.) ≤ /2 1

1

/16

> /2 – 1

3

/32

>1

1

1

Doc Ref: VT-1 – Rev. 2

Maximum Thickness of Reinforcement (in.)

/8

Page 14 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.4

Appendix 4 – API 650 Welded Tank for Oil Storage A weld shall be acceptable by visual inspection if the inspection shows the following:

10.4.1

There are no crater cracks, other surface cracks or arc strikes in or adjacent to the welded joints.

10.4.2

Maximum permissible undercut is 0.4 mm (1/64 in.) in depth for vertical butt joints, vertically oriented permanent attachments, attachment welds for nozzles, manholes, flush-type openings, and the inside shell-to-bottom welds. For horizontal butt joints, horizontally oriented permanent attachments, and annular-ring butt joints, the maximum permissible undercut is 0.8 mm (1/32 in.) in depth.

10.4.3

The frequency of surface porosity in the weld does not exceed one cluster (one or more pores) in any 100 mm (4 in.) of length, and the diameter of each cluster does not exceed 2.5 mm (3/32 in.).

10.4.4

The reinforcement of the welds on all butt joints on each side of the plate shall not exceed the following thicknesses:

Plate Thickness mm (in.)

Maximum Reinforcement Thickness mm (in.) Vertical Joints

≤ 13 ( /2)

Horizontal Joints

1

2.5 ( /32)

3

3 ( /8 )

1

> 13 ( /2) to 25 (1)

1

3 ( /8 )

1

5 ( /16)

> 25 (1)

5 ( /16)

3

6 ( /4 )

3

1

The reinforcement need not be removed except to the extent that it exceeds the maximum acceptable thickness or unless its removal is required by for radiographic examination. The finished surface of the weld reinforcement at the location of the radiograph shall either be flush with the plate or have a reasonably uniform crown not to exceed the following values: Plate Thickness mm (in.) ≤ 13 ( /2)

Maximum Reinforcement Thickness mm (in.)

1

1.5 ( /16)

1

1

2.5 ( /32)

> 13 ( /2) to 25 (1)

3

1

> 25 (1)

3 ( /8 )

10.4.5

Misalignment in completed vertical joints for plates greater than 16 mm ( 5/8 in.) thick shall not exceed 10% of the plate thickness or 3 mm (1/8 in.), whichever is less; misalignment for plates less than or equal to 16 mm ( 5/8 in.) thick shall not exceed 1.5 mm (1/16 in.).

10.4.6

In completed horizontal butt joints, the upper plate shall not project beyond the face of the lower plate at any point by more than 20% of the thickness of the upper plate, with a maximum projection of 3 mm ( 1/8 in.); however, for upper plates less than 8 mm (5/16 in.) thick, the maximum projection shall be limited to 1.5 mm ( 1/16 in.). The upper plate at a horizontal butt joint shall have a 4:1 taper when its thickness is more than 3 mm (1/8 in.) greater than the lower plate.

10.4.7

Roundness Radii measured at 0.3 m (1 ft) above the bottom corner weld shall not exceed the following tolerances: Tank Diameter m (ft)

Radius Tolerance mm (in.) 1

< 12 (40)

± 13 ( /2)

From 12 (40) to < 45 (150)

± 19 ( /4)

From 45 (150) to < 75 (250)

± 25 (1)

≥ 75 (250)

Doc Ref: VT-1 – Rev. 2

3

1

± 32 (1 /4)

Page 15 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.4.8

Plumbness The maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/200 of the total tank height. The out-of-plumbness in one shell course shall not exceed the permissible variations for flatness and waviness as specified in ASTM A 6M/A 6, ASTM A 20M/A 20, or ASTM A 480M/A 480, whichever is applicable. The maximum out-of-plumbness of roof columns, guide poles, or other vertical internal components shall not exceed 1/200 of the total height. The 1/200 criteria shall also apply to fixed roof columns. For tanks with internal floating roofs, apply the criteria of this section or Appendix H, whichever is more stringent.

10.4.9

Local Deviations Local deviations from the theoretical shape (for example, weld discontinuities and flat spots) shall be limited as follows: Deviations (peaking) at vertical weld joints shall not exceed 13 mm ( 1/2 in.). Peaking at vertical weld joints shall be determined using a horizontal sweep board 900 mm (36 in.) long. The sweep board shall be made to the nominal radius of the tank. Deviations (banding) at horizontal weld joints shall not exceed 13 mm ( 1/2 in.). Banding at horizontal weld joints shall be determined using a straight edge vertical sweep board 900 mm (36 in.) long. Flat spots measured in the vertical plane shall not exceed the appropriate plate flatness and waviness requirements given in 10.4.8

10.4.10 Nozzles Nozzles (excluding manholes) shall be installed within the following tolerances: Specified projection from outside of tank shell to extreme face of flange: ±5 mm ( 3/16 in.) Elevation of shell nozzle or radial location of a roof nozzle: ±6 mm ( 1/4 in.) Flange tilt in any plane, measured on the flange face: a.

±1/2 degree for nozzles greater than NPS 12 in nominal diameter

b.

±3 mm (1/8 in.) at the outside flange diameter for nozzles NPS 12 and smaller

Flange bolt hole orientation: ±3 mm (1/8 in.) 10.4.11 Shell Manholes Manholes shall be installed within the following tolerances: a.

Specified projection from outside of shell to extreme face of flange, ±13 mm ( 1/2 in.)

b.

Elevation and angular location, ±13 mm (1/2 in.)

c.

Flange tilt in any plane, measured across the flange diameter, ±13 mm ( 1/2 in.)

Doc Ref: VT-1 – Rev. 2

Page 16 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.5

Appendix 5 – AWS D1.1 Structural Welding Code – Steel

10.5.1

All welds shall be visually inspected and shall be acceptable if the following table is satisfied.

10.5.2

Visual Inspection Acceptance Criteria1 Table: Statically Loaded Nontubular Connections

Cyclically Loaded Nontubular Connections

Tubular Connections (All Loaded)

(1) Crack Prohibition Any crack shall be unacceptable, regardless of size or location.

X

X

X

(2) Weld/Base-Metal Fusion Thorough fusion shall exist between adjacent layers of weld metal and between weld metal and base metal.

X

X

X

(3) Crater Cross Section All craters shall be filled to provide the specified weld size, except for the ends of intermittent fillet welds outside of their effective length.

X

X

X

(4) Weld Profiles Weld profiles shall be in conformance in Section 10.5.3

X

X

X

(5) Time of inspection Visual inspection of welds in all steels may begin immediately after the completed welds have cooled to ambient temperature. Acceptance criteria for ASTM A514, A517, and A700 Grade 100 and 100 W steels shall be based on visual inspection performed not less than 48 hours after completion of the weld.

X

X

X

X

X

X

X

X

(B) The frequency of piping porosity in fillet welds shall not exceed one in each 4 in. [100 mm] of weld length and the maximum diameter shall not exceed 3/32 in. [2.5 mm]. Exception: for fillet welds connecting stiffeners to web, the sum of the diameters of piping porosity shall not exceed 3/8 in. [10 mm] in any linear inch of weld and shall not exceed 3/4 in. [20 mm] in any 12 in. [300 mm] length of weld.

X

X

(C) CJP groove welds in butt joints transverse to the direction of computed tensile stress shall have no piping porosity. For all other groove welds, the frequency of piping porosity shall not exceed one in 4 in. [100 mm] of length and the maximum diameter shall not exceed 3/32 in. [2.5 mm].

X

X

Discontinuity Category and Inspection Criteria

(6) Undersized Welds The size of a fillet weld in any continuous weld may be less than the specified nominal size (L) without correction by the following amounts (U): L specified nominal weld size, in. [mm] 3/16 [5] 1/4 [6] 5/16 [8]

U allowable decrease from L, in. [mm] 1/16 [2]. 3/32 [2.5] 1/8 [3].

In all cases, the undersize portion of the weld shall not exceed 10% of the weld length. On web-to-flange welds on girders, underrun shall be prohibited at the ends for a length equal to twice the width of the flange. (7) Undercut (A) For material less than 1 in. [25 mm] thick, undercut shall not exceed 1/32 in. [1 mm], with the following exception: undercut shall not exceed 1/16 in. [2 mm] for any accumulated length up to 2 in. [50 mm] in any 12 in. [300 mm]. For material equal to or greater than 1 in. thick, undercut shall not exceed 1/16 in. [2 mm] for any length of weld.

X

(B) In primary members, undercut shall be no more than 0.01 in. [0.25 mm] deep when the weld is transverse to tensile stress under any design loading condition. Undercut shall be no more than 1/32 in. [1 mm] deep for all other cases. (8) Porosity (A) CJP groove welds in butt joints transverse to the direction of computed tensile stress shall have no visible piping porosity. For all other groove welds and for fillet welds, the sum of the visible piping porosity 1/32 in. [1 mm] or greater in diameter shall not exceed 3/8 in. [10 mm] in any linear inch of weld and shall not exceed 3/4 in. [20 mm] in any 12 in. [300 mm] length of weld.

X

Note: An “X” indicates applicability for the connection type; a shaded area indicates non-applicability.

Doc Ref: VT-1 – Rev. 2

Page 17 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE FIGURE 5.4 ------ ACCEPTABLE AND UNACCEPTABLE WELD PROFILES

(A) Desirable Fillet Weld Profiles a

(B) Acceptable Fillet Weld Profiles

Convexity, C, of a weld or individual surface bead with dimension W shall not exceed the value of the following table WIDTH OF WELD FACE OR INDIVIDUAL SURFACE BEAD, W

MAX. CONVEXITY, C

W< 5/16 in. [8 mm] W > 5/16 in. [8 mm] TO W< 1 in. [25 mm] W > 1 in. [25 mm]

UNDERSIZE WELD

EXCESSIVE CONVEXITY

EXCESSIVE UNDERCUT

1/16 in. [2 mm] 1/8 in. [3 mm] 3/16 in. [5 mm]

OVERLAP

UNDERSIZE WELD

INCOMPLETE FUSION

(C) UNACCEPTABLE FILLET WELD PROFILES

BUTT PLATE – EQUAL THICKNESS PLATE b

BUTT JOINT (TRANSITION) – UNEQUAL THICKNESS PLATE

Reinforcement R shall not exceed 1/8 in. [3 mm] (see 10.5.3)

(D) ACCEPTABLE GROOVE WELD PROFILE IN BUTT JOINT

EXCESSIVE WELD REINFORCEMENT

UNDERFILL

EXCESSIVE UNDERCUT

OVERLAP

(E) UNACCEPTABLE GROOVE WELD PROFILES IN BUTT JOINTS Note: All welds shall meet the visual acceptance criteria of Table 6.1

Doc Ref: VT-1 – Rev. 2

Page 18 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.5.3

Weld Profiles All welds meet the visual acceptance criteria of Table in 10.5.2 and shall be free from cracks, overlaps, and the unacceptable profile discontinuities exhibited in Figure 5.4 except as otherwise allowed in 10.5.3. 10.5.3.1

Fillet Welds The faces of fillet welds may be slightly convex, flat, or slightly concave as shown in Figure 5.4. Figure 5.4(C) shows typically unacceptable fillet weld profiles.

10.5.3.2

Intermittent Fillet Welds Except for undercut, as allowed by the code, the profile requirements of Figure 5.4 shall not apply to the ends of intermittent fillet welds outside their effective length.

10.5.3.3

Convexity Except at outside welds in corner joints, the convexity C of a weld or individual surface bead shall not exceed the values given in Figure 5.4.

10.5.3.4

Groove or Butt Welds Groove welds shall be made with minimum face reinforcement unless otherwise specified. In the case of butt and corner joints, face reinforcement shall not exceed 1/8 in. [3 mm] in height. All welds shall have a gradual transition to the plane of the base-metal surfaces with transition areas free from undercut except as allowed by this code. Figure 5.4(D) shows typically acceptable groove weld profiles in butt joints. Figure 5.4(E) shows typically unacceptable weld profiles for groove weld butt joints. 10.5.3.4.1 Flush Surfaces Butt welds required to be flush shall be finished so as to not reduce the thicknesses of the thinner base metal or weld metal by more than 1/32 in. [1 mm], or 5% of the material thickness, whichever is less. Remaining reinforcement shall not exceed 1/32 in. [1 mm] in height. However, all reinforcement shall be removed where the weld forms part of a faying or contact surface. All reinforcement shall blend smoothly into the plate surfaces with transition areas free from undercut. 10.5.3.4.2 Finish Methods and Values Chipping and gouging may be used provided these are followed by grinding. Where surface finishing is required, roughness values (see ASME B46.1) shall not exceed 250 microinches [6.3 micrometers]. Surfaces finished to values of over 125 microinches [3.2 micrometers] through 250 microinches [6.3 micrometers] shall be finished parallel to the direction of primary stress. Surfaces finished to values of 125 microinches [3.2 micrometers] or less may be finished in any direction.

Doc Ref: VT-1 – Rev. 2

Page 19 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.6

Appendix 6 – ASME B31.1 Pressure Piping

10.6.1

Internal misalignment of the ends to be joined shall not exceed 1⁄16 in. (2.0 mm) unless the piping design specifically states a different allowable misalignment. When the internal misalignment exceeds the allowable, it is preferred that the component with the wall extending internally be internally trimmed to a 1:3 maximum slope. However, trimming shall result in a piping component thickness not less than the minimum design thickness and the change in contour shall not exceed 30 deg.

10.6.2

Socket Weld Assembly The depth of insertion of a pipe or tube into a socket weld fitting shall be at least 1/4 in. (6.0 mm). Before welding, there should be at least 1/16 in. (2.0 mm) clearance between the end of pipe and internal shoulder of the socket weld fitting. The inside diameter of the socket or sleeve exceed the outside diameter of the pipe or tube by more than 0.080 in. (2.0 mm).

10.6.3

Components with different outside diameter or wall thicknesses are welded together, welding end transmission shall provide for a maximum 30 degree angle across the weld with respect to the base metal (diameters) on each side of the weld. Additionally when both components to be welded (other than pipe to pipe) have a transition from a thicker section to the weld end preparation from a thicker section to the weld end preparation, the included angle between the surface of the weld and the surface of either of the components shall not be less than 150 deg.

10.6.4

As-welded surfaces are permitted; however, the surface of welds shall be sufficiently free from coarse ripples, grooves, overlaps, abrupt ridges, and valleys to meet the following:

10.6.5

a.

The surface condition of the finished welds shall be suitable for the proper interpretation of radiographic and other nondestructive examinations when nondestructive examinations are required.

b.

If the surface of the weld requires grinding to meet the above criteria, care shall be taken to avoid reducing the weld or base material below the minimum required thickness.

c.

Concavity on the root side of a single welded circumferential butt weld is permitted when the resulting thickness of the weld is at least equal to the thickness of the thinner member of the two sections being joined and the contour of the concavity is smooth without sharp edges. The internal condition of the root surface of a girth weld, which has been examined by radiography, is acceptable only when there is a gradual change in the density, as indicated in the radiograph. If a girth weld is not designated to be examined by radiography, a visual examination may be performed at welds which are readily accessible.

Fillet Welds In making fillet welds, the weld metal shall be deposited in such a way as to secure adequate penetration into the base metal at the root of the weld. Fillet welds may vary from convex to concave. The size of a fillet weld shall be as shown on the Detail or Erection Drawing a.

Slip-On and Socket Welding Flanges Weld Leg Length for socket and slip-on flanges shall be 1.4 times the nominal pipe wall thickness or thickness of hub, whichever is smaller.

b.

Socket Welding Components Other than Flanges Weld Leg Length for socket welding components other than flanges shall be 1.09 nominal pipe wall thickness or the thickness of the socket wall, whichever is smaller.

10.6.6

Seal Welds Where seal welding of threaded joints is performed, threads shall be entirely covered by the seal weld. Seal welding shall be done by qualified welders.

10.6.7

All completed welds in pipe and piping components shall be capable of complying with the acceptance standards specified below or with the limitations on imperfections specified in the material specification under which the pipe or component was furnished. The following indications are unacceptable: a.

Cracks — external surface.

b.

Undercut on surface which is greater than 1⁄32 inch (1.0 mm) deep.

c.

Weld reinforcement greater than specified in Table 127.4.2.

Doc Ref: VT-1 – Rev. 2

Page 20 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE Table 127.4.2

Reinforcement of Girth and Longitudinal Butt Welds Maximum Thickness of Reinforcement for Design Temperature

Thickness of Base Metal, in. (mm)

> 750°F (400°C)

350°F–750°F (175°C–400°C)

< 350°F (175°C)

in.

mm

in.

mm

in.

mm

Up to 1⁄8 (3.0), incl.

1

2.0

3

/32

2.5

3

5.0

Over ⁄8 to ⁄16 (3.0 to 5.0), incl.

1

2.0

1

3.0

3

5.0

Over ⁄16 to ⁄2 (5.0 to 13.0), incl.

1

2.0

5

4.0

3

5.0

Over 1⁄2 to 1 (13.0 to 25.0), incl.

3

2.5

3

/16

5.0

3

/16

5.0

Over 1 to 2 (25.0 to 50.0), incl.

1

3.0

1

6.0

1

6.0

Over 2 (50.0)

5

1 3

3

1

/16 /16 /16 /32 /8

/32

4.0

/8

/32

/4

/16 /16 /16

/4

The greater of ⁄4 in. (6 mm) or ⁄8 times the width of the weld in inches (millimeters). 1

1

GENERAL NOTES: (a)

For double welded butt joints, this limitation on reinforcement given above shall apply separately to both inside and outside surfaces of the joint.

(b)

For single welded butt joints, the reinforcement limits given above shall apply to the outside surface of the joint only.

(c)

The thickness of weld reinforcement shall be based on the thickness of the thinner of the materials being joined.

(d)

The weld reinforcement thicknesses shall be determined from the higher of the abutting surfaces involved.

(e)

Weld reinforcement may be removed if so desired.

d.

Lack of fusion on surface.

e.

Incomplete penetration (applies only when inside surface is readily accessible).

f.

Any other linear indications greater than 3⁄16 in. (5.0 mm) long.

g.

Surface porosity with rounded indications having dimensions greater than 3⁄16 in. (5.0 mm) or four or more rounded indications separated by 1⁄16 in. (2.0 mm) or less edge to edge in any direction. Rounded indications are indications which are circular or elliptical with their length less than three times their width.

Doc Ref: VT-1 – Rev. 2

Page 21 of 29

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.7

Appendix 7 – ASME B31.3 Process Piping (Except High Pressure Piping)

10.7.1

Fit-up, including misalignment of butt-welds, shall be in accordance with the WPS. Any misalignment of butt-welds, exceeding the WPS shall be tapered to a 30-degree maximum angle. The resulting weld joint and tapered areas shall not be thinner than the non-tapered base material. Figure 328.4.3

Trimming and Permitted Misalignment

(a) Thicker Pipe Taper-Bored to Align

(b) Thicker Pipe Bored for Alignment

10.7.2

Opening through the pipe for branch on pipe connections shall align with the bore of the branch within 3.2 mm (1/8 in.) or one-half the branch wall thickness, whichever is less.

10.7.3

The depth of insertion of a pipe or tube into a socket weld fitting shall be at least 1/4 in. (6.0 mm). Before welding, there should be at least 1/16 in. (1.5 mm) approximate gap between the end of pipe and internal shoulder of the socket weld fitting.

10.7.4

Fillet Welds In making fillet welds, the weld metal shall be deposited in such a way as to secure adequate penetration into the base metal at the root of the weld. Fillet welds may vary from convex to concave. The size of a fillet weld shall be as shown on the Detail or Erection Drawing a.

Double-Welded Slip-On and Socket Welding Flange Attachment Welds Weld Leg Length for socket and slip-on flanges shall be 1.4 times the nominal pipe wall thickness or thickness of hub, whichever is smaller.

b.

Socket Welding Components Other than Flanges Weld Leg Length for socket welding components other than flanges shall be 1 1/4 t (t = pressure design thickness) but not less than 3 mm (1/8 in.)

10.7.5

Seal Welds Where seal welding of threaded joints is performed, threads shall be entirely covered by the seal weld. Seal welding shall be done by qualified welders.

Doc Ref: VT-1 – Rev. 2

Page 22 of 29

Doc Ref: VT-1 – Rev. 2

A

A

A

E

G

A

A

N/A

K

L

Girth, Miter Groove & Branch Connection [Note (2)]

A

B

E

G

H

A

N/A

K

L

Fillet [Note (4)]

L

N/A

N/A

A

H

N/A

L

K

J

A

A

F

L

K

J

A

A

F

D

A

L

N/A

J

A

A

N/A

N/A

N/A

M

K

N/A

A

I

N/A

N/A

C

Girth and Miter Groove

D

A

C

M

K

N/A

A

A

N/A

N/A

A

A

M

N/A

N/A

A

H

N/A

N/A

N/A

N/A

A

M

K

N/A

A

H

N/A

N/A

B

A

A

Branch Connection [Note (2)]

N/A

Girth, Miter Groove & Branch Connection [Note (2)] A

Fillet [Note (4)]

N/A

Longitudinal Groove [Note (3)] A

Longitudinal Groove [Note (3)]

A

A

Fillet [Note (4)]

A

A

… …

… … … …

✓ ✓ … … ✓ …

… ✓ ✓ ✓ ✓ ✓

Undercutting Surface porosity or exposed slag inclusion [Note (5)]

Weld reinforcement or internal protrusion

Concave root surface (suck up)

Surface finish

Page 23 of 29

(d) Ellipsis (. . .) indicates examination method not generally used for evaluating this kind of weld imperfection.

(c) Check (✓) indicates examination method generally used for evaluating this kind of weld imperfection.

…

…

…

…

…

…

…

Internal slag inclusion, tungsten inclusion, or elongated indication

… ✓

…

Internal porosity

…

… ✓

✓

Incomplete penetration

…

… ✓

✓

Lack of fusion

✓

✓

✓

✓

Crack

Visual

A

Weld Imperfection

Radiography

A

Type of Weld

Examination Methods

Magnetic Particle

A

A

Type of Weld

Category D Fluid Service

Liquid Penetrant

GENERAL NOTES: (a) Weld imperfections are evaluated by one or more of the types of examination methods given, as specified in paras. 341.4.1, 341.4.2, 341.4.3, and M341.4, or by the engineering design. (b) “N/A” indicates the Code does not establish acceptance criteria or does not require evaluation of this kind of imperfection for this type of weld.

Longitudinal Groove [Note (3)]

A

Type of Weld

Severe Cyclic Conditions

Acceptance Criteria for Welds and Examination Methods for Evaluating Weld Imperfections

10.7.6

Normal and Category M Fluid Service

Table 341.3.2

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE

The acceptance criteria for welds are given in Table 341.3.2. Typical weld imperfections are shown in Figure 341.3.2.

YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE Criterion Value Notes for Table 341.3.2 Criterion Symbol

Measure

Acceptable Value Limits [Note (6)]

A

Extent of imperfection

Zero (no evident imperfection)

B

Depth of incomplete penetration Cumulative length of incomplete penetration

≤ 1 mm (1 ⁄ 32 in.) and ≤ 0.2Tw ≤ 38 mm (1.5 in.) in any 150 mm (6 in.) weld length

C

Depth of lack of fusion and incomplete penetration Cumulative length of lack of fusion and incomplete penetration [Note (7)]

≤ 0.2 Tw ≤ 38 mm (1.5 in.) in any 150 mm (6 in.) weld length

D

Size and distribution of internal porosity

See BPV Code, Section VIII, Division 1, Appendix 4

E

Size and distribution of internal porosity

For Tw ≤ 6 mm (1 ⁄ 4 in.), limit is same as D For Tw > 6 mm (1 ⁄ 4 in.), limit is 1.5 x D

F

Slag inclusion, tungsten inclusion, or elongated indication Individual length Individual width Cumulative length

≤ Tw /3 ≤ 2.5 mm (3⁄32 in.) and ≤ Tw /3 ≤ Tw in any 12 Tw weld length

G

Slag inclusion, tungsten inclusion, or elongated indication Individual length Individual width Cumulative length

≤ 2 Tw ≤ 3 mm (1 ⁄ 8 in.) and ≤ Tw /2 ≤ 4 Tw in any 150 mm (6 in.) weld length

H

Depth of undercut

≤ 1 mm (1 ⁄ 32 in.) and ≤ Tw /4

I

Depth of undercut

≤ 1.5 mm (1 ⁄ 16 in.) and ≤ [Tw /4 or 1 mm (1 ⁄ 32 in.)]

J

Surface roughness

≤ 500 min. Ra per ASME B46.1

K

Depth of root surface concavity

Total joint thickness, incl. weld reinf., ≥ Tw

L

Height of reinforcement or internal protrusion [Note (8)] in any plane through the weld shall be within limits of the applicable height value in the tabulation at right, except as provided in Note (9). Weld metal shall merge smoothly into the component surfaces

M

Height of reinforcement or internal protrusion [Note (8)] as described in L. Note (9) does not apply.

For Tw, mm (in.) ≤ 6 ( ⁄ 4) > 6 ( ⁄ 4), ≤ 13 (1 ⁄ 2) > 13 (1 ⁄ 2), ≤ 25 (1) > 25 (1) 1

1

Height, mm (in.) ≤ 1.5 (1 ⁄ 16) ≤ 3 (1 ⁄ 8) ≤ 4 (5 ⁄ 32) ≤ 5 (3 ⁄ 16)

Limit is twice the value applicable for L above

NOTES: (1)

Criteria given are for required examination. More stringent criteria may be specified in the engineering design. See also paras. 341.5 and 341.5.3.

(2)

Branch connection weld includes pressure containing welds in branches and fabricated laps.

(3)

Longitudinal groove weld includes straight and spiral seam. Criteria are not intended to apply to welds made in accordance with a standard listed in Table A-1 or Table 326.1. Alternative Leak Test requires examination of these welds; see para. 345.9.

(4)

Fillet weld includes socket and seal welds, and attachment welds for slip-on flanges, branch reinforcement, and supports.

(5)

These imperfections are evaluated only for welds ≤ 5 mm (3 ⁄ 16 in.) in nominal thickness.

(6)

Where two limiting values are separated by “and,” the lesser of the values determines acceptance. Where two sets of values are separated by “or,” the larger value is acceptable. Tw is the nominal wall thickness of the thinner of two components joined by a butt weld.

(7)

Tightly butted unfused root faces are unacceptable.

(8)

For groove welds, height is the lesser of the measurements made from the surfaces of the adjacent components; both reinforcement and internal protrusion are permitted in a weld. For fillet welds, height is measured from the theoretical throat, Fig. 328.5.2A; internal protrusion does not apply.

(9)

For welds in aluminum alloy only, internal protrusion shall not exceed the following values: (a) 1.5 mm (1 ⁄ 16 in.) for thickness ≤ 2 mm (5 ⁄ 64 in.) (b) 2.5 mm (3 ⁄ 32 in.) for thickness > 2 mm and ≤ 6 mm (1 ⁄ 4 in.) For external reinforcement and for greater thicknesses, see the tabulation for symbol L.

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YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE Fig. 341.3.2

Typical Weld Imperfections

Lack of fusion between weld bead and base metal

(a) Side Wall Lack of Fusion

(b) Lack of Fusion Between Adjacent Passes

Incomplete filling at root on one side only

Incomplete filling at root

(c) Incomplete Penetration due to Internal Misalignment

(d) Incomplete Penetration Of Weld Groove

External Undercut

Root bead fused to both inside surfaces but center of root slightly below inside surface of pipe (not incomplete penetration)

Internal Undercut

(e) Concave Root Surface (Suck-Up)

(f) Undercut

(g) Excess External Reinforcement

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YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE 10.0

Appendices

10.8

Appendix 8 - ANSI/AWWA D100-05 Welded Carbon Steel Tanks for Water Storage Any of the following weld defects identified by visual inspection shall be cause for rejection, and the deficient weld shall be repaired or replaced:

10.8.1

Any crack, regardless of size or location

10.8.2

Lack of fusion between adjacent layers of weld metal or between weld metal and base metal, except for tubular support columns for multiple column tanks, large diameter dry risers, and single pedestal columns with either a smooth cylindrical, conical, or bent plate surface as noted: a.

Circumferential Butt Joints One sided welds, some nonfusion more than ten (10) times the column wall thickness in length shall be rejected, provided that the governing stress is compression

b.

Longitudinal Butt Areas more than ten (10) times the column wall thickness in length shall be rejected.

10.8.3

Unfilled craters

10.8.4

Overlap resulting from the protrusion of weld metal beyond the weld toe or weld root

10.8.5

Weld size less than specified (insufficient throat or leg)

10.8.6

The thickness of the reinforcement of the welds on all butt joints shall not exceed the thicknesses given in Table 20. The reinforcement need not be removed except to the extent that it exceeds the maximum acceptable thickness or when required for radiographic inspections. In no case shall the face of the weld lie below the surface of the plates being joined Table 20

Maximum thickness of reinforcement for butt joints Maximum Thickness of Reinforcement

Plate Thickness in. (mm) 1

10.8.8

in.

< /2 (13)

3

> /2 (13) and < 1(25)

1

> 1 (25)

3

1

10.8.7

Vertical Joints /32 /8

/16

Horizontal Joints

(mm)

in.

(mm)

(2.4)

1

/8

(3.2)

(3.2)

3

/16

(4.8)

(4.8)

1

(6.4)

/4

Fillet weld convexity in excess of a.

1

/16 in. (1.6 mm) for width of individual bead or weld face not over 5/16 in. (7.9 mm)

b.

1

c.

3

/8 in. (3.2 mm) for width of individual bead or weld face over 5/16 in. (7.9 mm), but less than 1 in. (25.4 mm) /16 in. (4.8 mm) for width of individual bead or weld face 1 in. (25.4 mm) or over

Undercut in excess of the limits given as under: a.

For butt joints subject to primary stress due to weight or pressure of tank contents, maximum permissible undercut shall be 1/64 in. (0.4 mm).

b.

For butt joints subject to secondary stress, a maximum undercut of 1/32 in. (0.8 mm) is permitted, provided that the unwelded portion plus the undercut shall not reduce the thickness of the joint by more than one third of the thickness of the thinner plate joined.

c.

For lap joints subject to primary stress due to weight or pressure of tank contents, the maximum permissible undercut shall be 1/64 in. (0.4 mm).

d.

For lap joints subject to secondary stress, the maximum undercut permitted shall be 1/32 in. (0.8 mm).

e.

For butt joints in tension bracing, the finished surface of the splice weld shall be ground to eliminate sharp notches and all undercut shall be repaired to provide a smooth transition from the splice weld to the brace material (i.e., no undercut).

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YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE The maximum undercut permitted for all other joints shall be 1/32 in. (0.8 mm).

f. 10.8.9

Porosity: a.

Any visible porosity in butt joints subject to primary stress

b.

In all other joints, the sum of visible porosity greater than 1/32 in. (0.8 mm) in diameter shall not exceed 3/8 in. (9.5 mm) in any linear inch of weld and shall not exceed 3/4 in. (19.0 mm) in any 12 in. (305 mm) length of weld

10.8.10 Plumbness The maximum out-of-plumbness of the top of the shell relative to the bottom of the shell shall not exceed 1/200 of the total shell height. The out-of-plumbness in one shell plate shall not exceed the permissible variations for flatness and waviness as specified in ASTM A6 or in ASTM A20, whichever is applicable. 10.8.11 Roundness Radii measured at 1 ft (0.3 m) above the bottom corner weld shall not exceed the tolerances as given in Table 21. Table 21

Roundness—cylindrical shells Diameter Max ft

Radius Tolerance (m)

in.

(mm)

1

(13)

40

(12.2)

±1 /2

150

(45.7)

±1 /4

3

(19)

< 250

< (76.2)

±1

(25)

≥ 250

≥ (76.2)

±1 /4

1

(32)

10.8.12 Peaking and banding at weld joints Peaking is the out-of-plane distortion across a vertical weld seam. Banding is the out-of-plane distortion across a circumferential weld seam. 1. Using a horizontal sweep board 36 in. (0.91 m) long, peaking shall not exceed 1/2 in. (13 mm). 2. Using a vertical sweep board 36 in. (0.91 m) long, banding shall not exceed 1/2 in. (13 mm). 10.8.13 Localized flat spots. Flat spots (that deviate from the theoretical shape) measured in the vertical plane shall not exceed the appropriate plate flatness and waviness requirements in ASTM A6 and A20, whichever is applicable. 10.8.14 Plate Misalignment: The adjoining edges of butt joints shall be aligned accurately and retained in position during welding, so that the offset tolerances of Table 22 are not exceeded in the welded joint. Table 22

Maximum allowable offset of aligned butt joints

Thickness in.

Subject to Primary Stress

(mm) 5

in. 1

/8

5

t > /8

t > 16

/16

Lesser of 0.10t 1 or /4

(mm) 1.6 Lesser of 0.10t or 6

Subject to Secondary Stress in. 1

/8

Lesser of 0.20t 3 or /8

(mm) 3.2 Lesser of 0.20t or 9.5

*t = nominal thickness of the thinner plate at the joint

10.8.15 Minimum Size of Fillet and Seal Welds a.

Fillet Welds Plates 3/16 in. (4.76 mm) and less in thickness shall have fillet welds equal to the base metal thickness. Plates more than 3/16 in. (4.76 mm) thick shall have welds of a size not less than one-third the thickness of the thinner plate at the joint, with a minimum of 3/16 in. (4.76 mm).

b.

Adjustment for root opening Except for seal welds, the size of fillet welds shall be increased by the amount of root opening in excess of 1/16 in. (1.6 mm) and the root opening shall not exceed 3/16 in. (4.8 mm).

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YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE c.

Seal welds Seal welding, when specified or required by this standard, shall be accomplished by a continuous weld combining the functions of sealing and strength with weld sections changed only as required strength may necessitate. Seal welds shall be of minimum size, but sufficient to prevent cracking from thermal shrinkage. Seal weld acceptance shall be the same as for visual inspection of structural welds.

10.8.16 Minimum Length of Welds The minimum length of any weld shall be four times the weld size, but not less than 1 1/2 in. (38 mm). a.

Fillet welds The effective length of a fillet weld shall not include the length of tapered ends. A deduction of at least 1 /4 in. (6.4 mm) shall be made from the overall length as an allowance for tapered ends.

10.8.17 Intermittent Welding Intermittent welding shall not be used on tank-shell or riser surfaces in contact with tank contents or on plate surfaces exposed to external weathering a.

Length The length of any segment of intermittent welds shall not be less than four times the weld size but never less than 11/2 in. (38 mm).

b.

Seams Seams that are to have intermittent welds shall have continuous lengths of welds at each end for a distance of at least 6 in. (152 mm).

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YSC STANDARD VISUAL AND DIMENSIONAL TESTING PROCEDURE FORM 18077 Rev.01 Yanbu Steel Company P.O.Box 30075 Madinat Yanbu Al Sinaiyah Saudi Arabia Description/ Contract No.:

VISUAL INSPECTION REPORT

Report No.: Date:

Sheet:

Drawing No.:

Part No./Weld No.

Procedure & Rev. No.: VT-1 Rev. 01

Client:

Technique : Direct/Indirect

Material :

Acceptance Std.:

RESULTS OF VISUL EXAMINATION

INSPECTED BY Signature:_________________ Name: ___________________ Date: ____________________

Doc Ref: VT-1 – Rev. 2

REVIEWED BY Signature:_________________ Name: ___________________ Date: ____________________

CLIENT Signature:_________________ Name: ___________________ Date: ____________________

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