SECTION 2 Welding and Nondestructive Examination

201. General

1. All welds in the pressure boundary(vessel wall and pipe wall) of pressure-retaining equipment and piping systems and welds in mechanical load-bearing and structural components are to be made us- ing approved welding procedures by qualified welders and are to be inspected utilizing approved procedures by qualified technicians.

2. Critical sections of primary components are to be examined for surface and volumetric flaws to the extent specified in the design code, but not to a lesser extent than that specified in this Section.

3. All welders and welding operators to be employed in the manufacturing of equipment are to be properly qualified and experienced in the work proposed and the manufacturer is to employ a suffi- cient number of skilled supervisors to ensure a thorough supervision and control of all welding operations.

4. Unless otherwise expressly specified in this Section, requirements of Pt 2, Ch 2 of Rules for the Classification of Steel Ships may applied.

202. Welding

1. Welding procedures specification(WPS)

(1) A written WPS is to be prepared in accordance with ASME or ANSI/AWS D1.1 Code depend- ing on the equipment or component.

(2) The WPS is to describe in detail all essential and nonessential variables to the welding process employed in the procedure.

(3) Welding procedure specifications are to be qualified and the procedure qualification re-

cords(PQR) documenting the following data is to be submitted to the Society.

(A) Maximum hardness values (for well bore fluid service)

(B) Minimum and average toughness values for weld heat-affected zone and weld metal

(C) Minimum tensile strength

(D) Results from other tests required by the applicable code or standard

2. Welders and welder performance qualification tests

(1) Welders and welding operators are to be qualified by qualification tests conducted and evaluated

36 Guidance Relating to the Rules for the Classification of Mobile Offshore Drilling Units 2015

in accordance with the applicable code for each welding process and for each position used in production welding.

(2) Welder/welding operator qualification records are to be submitted to the Society.

3. Post weld heat treatment

(1) Accurate records of all heat treatments during fabrication, including rates of heating and cool- ing, hold time and soaking temperature are to be submitted to the Surveyor if required.

(2) Alternative methods of stress relief will be subject to special consideration by the Society

where post-weld heat treatment is not a requirement of the applicable manufacturing code.

203. Nondestructive examination

1. Non-destructive examination Procedures

NDE procedures specifying test method of each kind of nondestructive examination, extent of ex- amination and acceptance criteria are to be submitted to the Society for review

2. Qualification of nondestructive technicians

(1) The manufacturers are to certify that personnel performing and evaluating the non-destructive examination have been qualified and certified in accordance with the manufacturers' qualification system.

(2) The manufacturers' qualification system for qualification and certification of personnel perform- ing and evaluating the non-destructive examination examinations are to be written in accordance

with American Society for Nondestructive Testing SNT-TC-1A or equivalent.

(3) Certification documents of non-destructive examination Surveyor if required.

3. Timing of NDT

NDT should be conducted after Post Weld Heat Treatment

4. Extent of nondestructive examination

(ASNT) Recommended Practice No.

technicians are to be submitted to the

All weldments and other critical sections covered under 201. are to be subjected to 100% visual examination and nondestructive examination for surface and volumetric defects in accordance with this Annex or the relevant design code.

(1) All highly-stressed areas of forgings and castings of primary components used in well control are to be examined for flaws by methods capable of detecting and sizing significant internal defects.

(2)

Methods to detect surface flaws are also to be used in special applications. Substantiation is to be provided for areas exempted from examination in the terms of stress levels, quality control procedures at the foundry, forming or casting procedures, or documented historical data.

(3) Repair welds are to be subject to 100% surface NDE.

(4)

(5)

(6)

All welds of structural members considered special are to be inspected 100% by the ultrasonic or radiographic method.

Twenty percent of all welds of structural members considered primary are to be inspected by

the ultrasonic or radiographic method.

Welds of structural members considered to be secondary are to be inspected by the ultrasonic or radiographic method on a random basis.

(7) In locations where ultrasonic test results are not considered reliable, the use of magnetic-particle or dye-penetrant inspection as a supplement to ultrasonic inspection is to be conducted.

(8)

Welds for mechanical load-bearing components or pressure-retaining equipment are to be exam-

ined by nondestructive methods capable of detecting and sizing significant surface and internal defects.

5. Methods of nondestructive examination and acceptance criteria

Methods of nondestructive examination and acceptance criteria is to be in accordance with the fol- lowing Table 3.1.

Guidance Relating to the Rules for the Classification of Mobile Offshore Drilling Units 2015 37

Table 3.1 Methods of nondestructive examination and acceptance criteria

204. Record retention

The manufacturer is to maintain the following records after completion, and made available to the Surveyor upon request.

1. Weld Procedure Specification

2. Procedure Qualification Records

3. Welder/welding operator performance test records, including the date and fication of work assigned to each welder

these records are to be

test results and identi-

4. A record providing traceability and capable of identifying the welders who ing on particular part

have carried out weld-

5. Qualification records for all personnel performing nondestructive of examination

6. Nondestructive Examination records, including radiographs

examinations and evaluating results

38 Guidance Relating to the Rules for the Classification of Mobile Offshore Drilling Units 2015