NATIONAL WATER COMPANY Riyadh, Kingdom of Saudi Arabia
EXECUTION OF RIYADH CITY WATER SUPPLY- MAINLINE CONTRACT No. 11 Project Code: RW0104
Document Code: DKS-MS-C11-001
METHOD STATEMENT FOR WELDING OF CARBON STEEL PIPES
Contractor:
Method Statement
Consultant:
Client:
DKS-MST-C11-001 REV. 1
Table of Contents
1.0
Purpose
2.0
Scope of work
3.0
Definition and abbreviation 3.1
Definition.
3.2
Abbreviation.
4.0
Reference
5.0
Responsibilities.
6.0
Dongho Welding Procedure 6.1
General.
6.2
Procedure Qualification.
6.3
Qualification of Welding Procedure.
6.4
Procedure Qualification Record.
6.5
Qualified Procedure.
6.6
Qualification of Welders.
7.0
Procedure
8.0
Reject Rates
9.0
Criteria for approval or disapproval
10.0
Attachment
Method Statement
DKS-MST-C11-001 REV. 1
1.0
Purpose The purpose of this document is to lay down safe, fast and professional procedures for the welding of carbon steel pipes to comply with designated standards and specifications in accordance with accepted codes of practice. It is written in such a way that it covers the vast majority of welding situations envisaged. In the event of a situation arising that is not adequately covered a separate appendix peculiar to that situation will be published. This method statement or process specification provides the minimum requirements that govern the Flux Cored Arc Welding (FCAW), Gas Metal Arc Welding (GMAW) and Shielded Metal Arc Welding (SMAW) of carbon steel pipes with grade (API 5l X52). Design procedural and quality assurance requirements are given. All work instructions and Weld Procedure Specifications (WPS) used during welding shall satisfy the requirements of this process specification. This documentation also gives the requirements for preparing, qualifying and use of the Procedure Qualification Records (PQR).
2.0
Scope of Work Contractor shall perform the installation of carbon steel pipes with diameters ranging from 1400 up to 2400 millimeters at work site in an approved manner by consultant / National Water company (NWC). The work includes site preparation, pipe alignment, welding and coating, repair, cleaning and testing. Dongho Korean Saudi Ltd. Co. shall furnish all the required data regarding materials, manpower, and equipment and commence the work with prior approval by consultant (TYPSA) / National Water company (NWC). This Standard covers the requirements for qualifying all welding,
3.0
Definition and abbreviation:
3.1
Definition
Company
National Water Company (NWC)
Consultant
TYPSA
Contractor
Dongho Korean Saudi Limited Company
Third party
Alhoty Stanger LTD Co. perform Welding & NDE services
Method Statement
DKS-MST-C11-001 REV. 1
3.2
4.0
Abbreviation
WPS
Welding Procedure Specification
PQR
Procedure Qualification Records
WPQ
Welding Procedure Qualification
NDT
Non-Destructive Testing
DT
Destructive Testing.
RT
Radiographic Testing
UT
Ultrasonic Testing
VT
Visual Testing
MT
Magnetic test
PT
Penetrant test
CSWIP
Certification Scheme for Personnel
FCAW
Flux Cored Arc Welding
AWS
American Welding Society
WPR
Welder performance Qualification Record
Shall
A provision that is binding (mandatory)
Should
A provision that is optional (non-mandatory)
Reference 4.1
Design Drawing
4.2
Project Reference Documents
Method Statement
4.2.1
Project Quality Plan (DKS- PLN - C11-001 REV. 0)
4.2.2
Pipe laying Method Statement (DKS- MST-C11-001 REV. 0)
4.2.3
Pipe laying Inspection and test Plan (DKS- ITP-C11-001 REV. 0)
4.2.4
Pipe welding Method Statement (DKS- MST-C11-002 REV. 0)
4.2.5
Pipe welding Inspection and test Plan (DKS- ITP-C11-002 REV. 0)
4.2.6
Pipe coating Method Statement (DKS- MST-C11-003 REV. 0)
4.2.7
Pipe coating Inspection and test Plan (DKS- ITP-C11-003 REV. 0)
4.2.8
welded pipe Hydro-test Method Statement (DKS- MST-C11-004 REV. 0)
DKS-MST-C11-001 REV. 1
4.3
5.0
Project Applicable Codes and Standards
0.1
ANSI B31.4
Pipeline Transportation for Liquid Hydrocarbon
0.2
API 1104
Standard for Welding Pipeline
0.3
ASTM A370/E92
American Standard of Testing Materials
0.4
ASME Section V
Non-Destructive Testing (NDT) Examination
0.5
ASME Section IX
Welding and Brazing Qualifications
0.6
AWWA C206
Standard for field welding of steel water pipe
0.7
AWS D1.1
Structural Welding code steel
0.8
AWWA C203
0.9
AWWA C214 Standard for tape coating for the exterior of steel water pipeline.
Standard for Coal-tar protective coating and lining for steel water pipe line
Responsibilities 5.1
Contractor Responsibilities 5.1.1
Prepare weld test coupons in accordance with the WPS.
5.1.2
Have the testing laboratory record and certify the test results of the procedure qualification. The test certificate shall be attached to the PQR.
5.1.3
Verify that the WPS and the results of testing as reported in the PQR meet the requirements of the applicable Code.
5.1.4
All welding procedures to be used in this project shall be submitted on these forms include: •
Welding Procedure Specification (WPS)
•
Welding Procedure Qualification (WPQs)
5.2
Within Dongho Construction Division, ultimate responsibility for all installation and welding activities normally lies with the various Area Managers. In certain instances, for major projects, a separate project manager with total responsibility for that project may be appointed.
5.3
Every site, of whatever size, is run as a separate entity with an individual designated as being responsible to the Area Manager concerned for that particular site. The site organization obviously varies depending upon the size of the job. A typical site organization is shown at Annexure- 1.
The main duties of the key site personnel are as follows: a. Duties of Site Manager
Method Statement
•
Dongho’s representative on site responsible for all contractual relationships with the client/ consultant.
•
Ultimate responsibility for Quality Control of materials, construction components and methods of construction.
DKS-MST-C11-001 REV. 1
•
Duties of the Field Welding Engineer The following highlight the primary duties of the Field Welding Engr.:
1. Monitor that Safety and Environmental requirements are being met Generate Field Material Requisitions for welding related equipment, consumables, and tools according to site welding requirements 2. Train welders and Welder Training Instructors in accordance with site standards and Standard Work Process. 3. Identify any need for welder upgrading or training, and when required, request assistance from Welding & NDE services for such upgrading or training when required 4. Assure that all field welding is done in accordance with the current revision of the Welding Procedure specification and relevant Codes. 5. Assure that radiography, magnetic particle and liquid penetrant examinations comply with Code and project requirements. 6. Generate NDE requests. 7. Evaluate all NDE results. 8. Maintain visual surveillance of field fit-up and welding operations. 9. Be responsible for surveillance of all welding being performed at site. 10. Issue weekly reports in accordance with the applicable project standard and send copy to the quality Manager. 11. Prepare a project welding history at the completion of the project and submit copy to quality Manager. This report should include topics such as historical numbers of welders; reject rates, subcontractor performance, consumable and NDE/ PWHT costs, and lessons learned.
b. Welding Supervisor: Directing those operations associated with weldments in accordance with the appropriate contract documents and codes to produce a satisfactory product.
• • c.
Welding inspector Inspection of welding processes includes NDE control.
•
d. Quality Control Supervisor •
6.0
Ensure that all raw materials or proprietary products to be incorporated in the works are in accordance with the agreed specifications.
Dongho Welding Procedure 6.1
General
All welding procedure specifications and welding procedure qualification records shall conform to the requirement of the standard and the applicable codes. The weldment shall prove that a weldment will provide the desired properties for construction. Where no qualification code is applicable, the authorized persons of the consultant / Company shall decide. The changes are essential variable like Method Statement
DKS-MST-C11-001 REV. 1
process and material group etc.; needs separate qualification. All other changes over non-essential variable need revision of relevant WPS.
6.2
Procedure Qualification
Welding Procedure Specification Definition before production welding is started, a written procedure shall be established and qualified based on applicable codes, standard and good engineering practice, listing the material detailed method and parameters to be employed during welding, to demonstrate that the given weld will have suitable properties and soundness. The qualification weld has to be subjected to Non Destructive Testing (NDT) examination. Welding Procedure Specification (WPS) will be performed in accordance to the welding Procedure Qualification Record (WPQs).
6.3
Qualification of Welding Procedure Specification (WPS) 6.3.1
General The WPS is intended to provide direction for the welders and shall be readily available. All testing will be done by one experienced test laboratory to perform all the NDT (RT) and DT examination (Tensile & Bend). .
6.3.2
6.3.3
Welding Procedure Qualification (WPQ) •
All WPQs shall be performed in accordance to the Preliminary WPS.
•
The Qualification Test welds shall be performed simulating production welding shall be subjected to non-destructive testing and destructive testing.
•
All welding parameters and condition influencing the essential variables recorded using calibrated equipment.
•
The Quality of the Qualification Test Welds shall be determined by the required testing NDT, including VT, RT or UT. Tensile test bend in accordance with requirement of referred codes/standards (AWS D1.1) and contrast specification will be carried out by an approved laboratory.
•
The Non-Destructive Testing (NDT) shall only be performed using the approved equipment and procedure that can be employed for production.
will be
Test of Qualification Welds •
General a. Test Assembly shall be prepared with pipe material. b. All qualification welds shall be subjected to NDT after completion of welding. c.
•
The pipes & fittings shall be supplied with API-SLIANSI B16-25 Bevels.
Non-Destructive Testing (NDT) NDT shall consist of the following: a. Visual Inspection by CSWIP Inspector or equivalent. b. X-ray, UT, one of these methods shall be done for welding joint. c.
MT or PT shall be done as an additional method test to RT or UT.
d. The test results obtained from laboratory will be submitted to consultant / Company for approval and will be kept in records at site office. Method Statement
DKS-MST-C11-001 REV. 1
6.3.4
Qualification of Welding Repair Procedure •
All repairs welding shall be performed in accordance of the approved WPS and repairs completion shall be confirmed by using the same NDT method which detects the defect weld; repairs welding shall be executed by qualified welders.
•
Weld repairs shall be made under the direct control of the Welding Supervisor. It is also necessary that the Welding Supervisor be able to demonstrate that all required repairs have been made and reexamined. The Welding Supervisor, or a welding foreman, personally controls all weld repair activities. These include: a. lay out of area to be repaired b. selection of welder(s) who will perform the repair (for repairs grinding is considered to be an activity that should be performed by a welder) c. provide direction to the repair personnel d. inspect the repair cavity prior to any required re-welding by using (VT and MT) e. gives permission to proceed with repair welding f.
visually inspect the completed weld
g. perform or arrange the required NDE of the joint after the repair has been completed.
6.4
•
The visual inspection acceptance criteria to determine the unacceptable defect is Table 6.1 –AWS D1.1 (attached acceptance criteria)
•
The radiographic inspection acceptance criteria to determine the unacceptable defect is API Standard 1104. (attached acceptance criteria)
Procedure Qualification Record The Procedure Qualification Record (PQR) is a unique numbered written document containing all the information concerning the welding of the qualification joint, procedural information as run parameters, detailed methods and condition.
6.5
Qualified Procedure When all the required tests have been accepted and procedures have been qualified, WPS & PQR will be submitted to the client after approval by consultant with separate transmittal.
6.6
Method Statement
Qualification of Welders 6.6.1
Welders who passed the Procedure Qualification Test welds are confirmed as qualified welder.
6.6.2
Qualified welder (visual test) of their weld run or specimen will be tested by NDT at the weld location. DKS-MST-C11-001 REV. 1
7.0
6.6.3
Qualification shall be valid of 6 months unless otherwise stated in the applicable standard.
6.6.4
Welder Performance Record (WPR) shall be maintained showing the number of welds and NDT results for each welder.
6.6.5
Each welder shall identify the position of each weld with his ID.
6.6.6
A unique identification number shall be assigned to each welder and welder ID card showing welder name, ID number, welder photograph, all this data shall be recorded in the WPR.
Procedure
7.1
Human Resources
No
Direct Manpower:
QTY
1
Site manager.
1
2
Safety officer
1
3
Welding Supervisor.
1
4
Welding inspector.
1
5
Quality control supervisor
1
6
Welding foreman
1
7
Welders
12
8
Equipment Operators
3
9
Drivers
3
10
Pipe Fitters
3
11
Skilled Grinders
3
12
Laborer
40
7.2
No 1
Method Statement
Equipment
Equipment Mobile Crane 100 Tons
QTY
2
DKS-MST-C11-001 REV. 1
2
Mobile Crane 70 Tons
1
3
Lorry Crane
1
4
Welding Machine (Diesel), Meller
12
5
Dyna Truck
3
6
Semi-automatic GMAW M/C
Unit
7
7
Machinised FCAW M/C Unit
7
8
Water Tanker
1
9
Ambulance
1
7.3
Safety and Health
7.3.1
Specific Safety Precautions 1. Welders should not interfere or tamper with welding equipment. 2. Welders must wear protective clothing and eye protection when welding or chipping slag from welds. 3. A fire extinguisher should be kept in close proximity to welding operations, the CO or foam types being most suitable for general usage. 4. Any combustible material should be removed from the vicinity of welding operations; where removal is not possible the material should be protected. 5. The area around the welding operation should be cordoned off to protect other people from welding sparks or spatter. 6. In case of electric shock insulate welder from work place and ground using dry insulation. 7. Wear dry gloves in addition to other safety wears. 8. Do not touch electrically hot parts or electrode with bare skin or wet clothing. 9. Keep electrode holder and cable insulation in good condition.
7.3.2
Welding Process 1. The mains supply to the welding plant should be transformed down to a safe working voltage (usually between 80 and 110 volts). 2. The actual welding circuit should be isolated from the mains. 3. Trailing leads should be as short as possible, armored, and visible to avoid trip hazards or damage. 4. All equipment should be properly earthed. 5. All connections should be made with proper fittings or equipment.
Method Statement
DKS-MST-C11-001 REV. 1
6. Connection to the work to be welded should be made with clamps or lugs. 7. When not in use, all welding equipment should be disconnected from the mains supply, or isolated, and protected if left unattended for any length of time. 8. Particular care must be exercised in damp weather to avoid contact with the welding electrode or holder. 9. Electrode stubs should be ejected into a metal container or other non-combustible receptacle. 7.3.3
Cutting Grinding during 1. Always do an inspection on equipment before use to avoid injuries. 2. Grinder to be with dead man switch and without any locking arrangement. 3. Wear the correct PPE for the grinding/cutting operation. -
Double Eye protection (Glasses & face shield) Spats Apron Gloves
4. Take the grinder with both hands and hold it firmly before start of the operation. 5. When the grinder is switched off, hold it in your hands until the disk has stopped turning. 6. Keep the grinder away from the body parts and avoid any loose clothing near any rotating parts of the grinder 7. Make sure that the sparks do not fly in the direction of other workers 8. Do not drop the grinder or any other object onto the grinding wheel as it may crack the wheel. 9. Place all the off cut material in a container to avoid any injuries or tripping hazards 10. If the grinder is not in use, disconnect it from the power source and put in safe
place for storage or take back to the store.
7.3.4
Fit-Up and Assembly of Piping Components 1. Ensure proper support to pipes to prevent fall of it. 2. Be attentive while manual handling. Proper coordination between workers is must to prevent tripping hazard. 3. Use other PPE’s like safety shoes, safety glass, helmet, hand gloves.
7.3.5
Pre heating / Flame cutting 1. Keep fire extinguisher ready to use. 2. Remove combustibles & flammables from work area. 3. Check all cords are in good condition.
Method Statement
DKS-MST-C11-001 REV. 1
4. Wear required PPE’s. (Hand gloves, safety glasses, Face shield, Helmet, safety shoes, masks) 7.3.6
Carry out Radiography of welding joints 1. Take necessary Radiography permit. 2. The authorized person conducting radiography must be approved by the Supreme Council. 3. The person should be possessing dosimeter all the time. 4. Area to be barricaded indicating the radiation symbol from all the sides. 5. No un-authorized person should be allowed to enter the working area.
6. The barricading must be done up to the area where the radiation shows on the meter is 25 mrem/ hr using calibrated instrument. 0.01 rem = 1 mrem = 0.01 mSv 0.01 rem = 10 mrem = 0.1 mSv 0.1 rem = 100 mrem = 1 mSv = 0.001 Sv 1 rem = 1000 mrem = 10 mSv = 0.01 Sv 10 rem = 100 mSv = 0.1 Sv 100 rem = 1000 mSv = 1 Sv (Sievert) 1000 rem = 10 Svv 7.3.7
Positioning of crane and Trailer truck 1. Position the crane on solid ground 2. Outriggers fully extended on pad. 3. Free at least 1.5 m away from edge of excavation or weak ground conditions 4. All equipment must be inspected by Safety officer. 5. Operator to conduct daily check of crane and rigging. 6. Operator and Banksman with visibility vest. 7. Operator to sound horn while swinging the boom 8. Crane’s flickering lights on while working load / boom. 9. Barricade the area of activity 10. Banksman / Rigger to wear reflective vest. Signal procedure to be followed. Unauthorized persons to be removed from the site. 11. Crane to be positioned after studying site condition and providing enough setback from adjacent working area.
Attached Job Safety analysis (JSA) – on site underground pipe welding.
1.1
Complete welding Procedure 1.1.1
Method Statement
Documentation and certificates requirement DKS-MST-C11-001 REV. 1
1. The changes in essential variables like process and material group needs separate qualification. 2. All other changes over non-essential variables need revision of relevant WPS. 1.1.2
The document is designed to be read in conjunction with the Project quality plan (DKS- PLN - C11-001 REV. 0) 3. This document covers the construction and installation of pipelines. 4. The contractor shall prepare and submit the originals or legible copies of WPS, PQR and test certificates. 5. Welding may not commence until the written approval of the consultant to National Water Company or Representative has been obtained. Copies of the approved WPS, PQR and test reports shall be retained to contractor.
1.1.3
Pipes’ identification, traceability All welding work shall be fully traceability by using: 1. Pipe-Weld Log Book has to be written clearly the data of each pipe and the weld number uniquely with all recorded information. 2. Numbering the weld joints and kilometric reading should be marked on the weld joints. 3. Welding NDT report should be daily updated and maintained. 4. Welder’s ID by which weld he will recognized for welding.
1.1.4
Reception of pipes in the site 1. All pipes shall be inspected upon receipt by QC inspector. 2. Pipe body repair by welding will not be allowed. 3. Material handling and storage as per pipe laying MST (DKS- MST-C11-001 REV. 0).
1.1.5
Preliminary inspection and preparation 1. When starting a new stringing of the pipes the bevel ends shall be inspected. 2. Welded pipe stringing should be end capped. 3. The bevel shall be designed in accordance with the approved WPS. 4. In case bevel required modification or machining, grinding or machine thermal cutting shall be used and then Magnetic Particle Testing (MPT) shall be done.
1.1.6
Location on the trench and alignment between pipes 1. External clamp shall be used for mainline and Tie-In. 2. All pipes shall be checked before the start of welding activities to determine that the pipe is ready to commence. The inspection should be done as the followings: a. Pipe bevels are free of nicks and gouges in addition to the surrounding area shall be free from contaminants such as oil grease etc. for not less than 25mm from welding edge on both inside and outside the pipe. b. Pipe ends are uniform and circular with no indication of flatting or denting.
Method Statement
DKS-MST-C11-001 REV. 1
c.
Pipe bevels shall be designed in accordance with the approved WPS.
d. In case the bevels are not matching with the WPS, pipe end shall be beveled by machining, grinding or machine thermal cutting. e. Maximum misalignment shall not be more than 3 millimeters as per API 1104, offsets greater than these limits are due to variation of weather temperature and may be either corrected by rotating, machining or grinding the pipe to give 1:4 taper at transition, providing minimum designed Wall Thickness is maintained. f.
Fittings (bends, tees & branches) require for pipe line shall be fabricated locally.
g. Pipe for welding shall be setup and correctly spaced allowing for temperature change during welding. h. Fit-Up the joint will be done by using side boom or equivalent lifting equipment with non-metallic slings and cables with External clamp. i. 1.1.7
Clamp can be removed after completing the 70% of Root
Weather conditions 1. Weather Conditions a. All the welds during welding operation shall be protected from wind, sand and rain and a suitable tent with all accessories shall be used. 2. Pre-Heating Inter-pass Temperature Control a. As stated in the WPS if Pre-Heat is required a heaters or propane torches shall be used. b. The Temperature shall be checked immediately in all Heat Affected Zones (HAZ) using heat temperature gauge. c.
1.1.8
The inter-pass temperature shall not be exceed than that recorded in the WPS.
Welding
External clamp used to align pipes, and then pipe ends are gapped.
Two welders simultaneously weld root pass, by SEMIAUTOMATIC STT PROCESS FOR ROOT PASS or SMAW.
Root run by MIG- solid wire (ER-70S.3) or electrode (E6010) brand name ESAB as attached catalog
Hot and Fill Pass by RAILTRAC- FCW by wire (E71T1) or electrode (E7010) brand name ESAB attached catalog.
Round tracks for Orbital GMAW welding
Mechanized FCAW Cap Passes
1. Welding Process a. Welding Consumable Materials b. The welding electrode shall be listed in WPS. c. Method Statement
Trade names & certificate shall be kept at site during welding operation. DKS-MST-C11-001 REV. 1
d. Welding consumable & materials shall be kept and handled as per manufacture's recommendation & procedure. 2. Welding Operation a. Welding Process and Consumable Welding Electrodes b. Welding shall be performed by Butt weld groove V as per the WPS. c.
Welding & filler metal consumable electrodes shall be identified as per WPS shall be used trade name certificate shall be kept at the site during welding operation.
d. Welding electrode used shall conform to the requirement of the AWS Specification. e. Roof pass of the production butt weld shall be deposited using suitable material. 3. Main Line Welding a. All pipes will be welded in the trench. b. Pre-Heating of min 50oC if the ambient temperature of the pipe is below 10oC and to 100oC if the ambient temperature is below 0oC as per WPS. c.
Root & Hot pass shall be done by two qualified welders as stated in the WPS.
d. Filling metal and Caps can be started up by two qualified welder as stated in the WPS. e. All welds shall be completed by a continuous one day. f.
Not completed weld can be left for next day in case 40% of the welds are completed.
g. All Arc burns beside the weld bevel or ground clam arc burns shall be removed by grinding. h. When the pipe is welded above the ground the clearance surrounding the pipe shall be not less than 400 mm. i.
During welding, all slag, spatter and excessive weld build up shall be removed from the weld and the adjacent area using power tools.
4. Tie-In Welding a. Using suitable lifting equipment as per lowering procedure. b. Tie-in shall be fitted-up by side boom or crane and external clamp. c.
Tie-in welds shall be performed by two qualified welders.
d. Lifting equipment or the Side boom can be removed after completing 75 % of the root weld. e. Proper plugging one end shall be done during welding operation to avoid development of air draughts. f.
The welding shall not be interrupted until the joint has been completely finished.
g. Filling and capping passes can be done uphill or downhill progression. h. When the pipe is welded in a trench and all tie-in, the clearance shall be enough to give the welder suitable access to the joint. Method Statement
DKS-MST-C11-001 REV. 1
1.1.9
Coating
1.1.10
The joint shall be coated and lined with a coating system compatible with that on the body of the pipe, in accordance with the requirements for field repairs set forth in the appropriate AWWA C203 which is comply with AWWA C214 coating or lining standard and Pipe coating Method Statement (DKS- MST-C11-003 REV. 0)
1.1.11 Inspection and tests 1.1.12 The contractor shall carry out the inspection of the production welds to ensure that all production welds meet the requirement standard and approved specification. Therefore, the inspection and tests shall be done in accordance with the project inspection and test plan (DKS-ITP-C11-002 REV. 0) approved by consultant /company. a. Visual Inspection of pipe material certificate, data, external coating and internal lining. b. All types of inspection which has been approved in the welding procedure in accordance to the standard. (API-1104 & AWS D1.1) c.
Final inspection should be done as per Quality Control Plan (QCP) before hydro testing commenced.
d. Tests for welds e. Hydro test procedure. Method Statement. 1.1.13 Documentation and Quality Procedures Qualified welding procedures that have been approved by Client Management may be used on several jobs or projects but they shall be resubmitted to NWC Inspection, for each new job for approval. If there is a question regarding the suitability of a procedure for a particular application, the procedure shall be submitted by inspection to the client’s representative for review and approval.
8.0
Reject Rates •
Reject rates are the total welds rejected expressed as a percentage of the total welds examined by NDE, not the "amount" of rejected weld. For example, consider two cases where large diameter pipe is being welded:
Method Statement
Case 1
Case 2
100 Total Joints
100 Total Joints
10 Rejected Joints
2 Rejected Joints
Each requiring 1 inch of repair
Each requiring 15 inches of repair
Reject Rate = 10 Percent
Reject Rate = 2 Percent
Total length of weld repair is 10 inches
Total length of weld repair is 30 inches
DKS-MST-C11-001 REV. 1
In Case 1 the reject rate is 10 percent and the total length of repair is 10 inches, while in Case 2 the reject rate is only 2 percent but the total length of repair is 30 inch •
9.0
When reject rates exceed 10 percent, the welding Engr. is expected to determine the causes, and recommend solutions to bring the reject rate percentages back to an acceptable level. The welding Engr. may need to recommend a change in welders or re-qualify/upgrade current welders. Procedure and/or technique changes may also be involved. The welding Engr. may contact the third party Welding and NDE Services.
Criteria for approval or disapproval Unless specified otherwise by the client, consultant or other authority, American standards and codes of practice will be followed by example (AWWA C206, AWWA C203,C214, API 1104 and AWS D1.1).
10.0
Attachment
1. Annex No - 1. A typical site organization is shown at 2. Annex No. -2- Shrinkable Sleeve Coating Inspection Report Form, one page. 3. Annex No. -3 Visual, Holiday Detection, Peel Test and Air Voids Inspection Report Form, one page. 4. Annex No. –applicable code and Standard acceptance criteria.
Method Statement
DKS-MST-C11-001 REV. 1
