AWWA C200 standard covers electrically butt-welded straight-seam or spiral-seam pipe and seamless pipe 6 in. (150 mm) in nominal diameter and larger for the transmission and distribution of water or for use in other water system facilities.
All work performed and material furnished under this standard may be inspected by the purchaser, but such inspection shall not relieve the manufacturer of responsibility to furnish material and perform work in accordance with this standard.
The manufacturer shall maintain a quality-assurance program to ensure that minimum standards are met. It shall include a certified welding inspector (AWS QC1) to verify that welders and welding procedures are qualified, procedures are being followed with limitation of testing, and quality-assurance functions are being implemented.
The finished pipe shall be free from unacceptable defects. Defects in seamless pipe or in the parent metal of welded pipe will be considered unacceptable when the depth of the defect is greater than 12.5% of the nominal wall thickness.
The repair of defects will not be permitted if the depth of the defect exceeds 1/3 of the nominal wall thickness of the pipe and if the length of that portion of the defect in which the depth exceeds 12.5% is greater than 25% of the outside diameter of the pipe. Each length of repaired pipe shall be tested hydrostatically in accordance with standard requirements.
If the pipe is to be manufactured to meet the requirements of one or more of the ASTM specifications, the grades of pipe shall be :
- Type E or S for ASTM A53
- A-36, A-283, A-570, A-572 for ASTM A134
- All grades for ASTM A135
- All grades for ASTM A139
When the pipe is to be fabricated to meet the standard requirements; the plates, the sheets, or the coils shall be selected in accordance to the following physical properties and specifications.
- ASTM A-36/36M, ASTM A-283/A-283M – Grade C et D
- ASTM A-572/A-572M – Grade 42,50 and 60
COILS AND SHEETS
- ASTM A-570/570M – Grade 30 to 50.
For plates, the maximum allowable thickness variation shall be 0.010“ under the ordered thickness.
For the sheets, the maximum allowable thickness variations shall be in accordance to the ASTM A-568 specifications.
Pipe produced in a pipe mill shall be subjected to AWWA C-200 quality-control procedures. Such pipe shall be manufactured to meet the standard requirements of ASTM A53, ASTM A134, ASTM A135 and ASTM A139.
FABRICATION OF PIPE
The weld shall be reasonably uniform width and height for the entire length of the pipe.
By agreement between the purchaser and the manufacturer, the welding can be done either by automatic or manual means.
All spiral, longitudinal, and girth seams used in the manufacture of the pipe shall be full-penetration welded butt joints.
The maximum radial offset tolerance on the plates is :
- For thickness of 3/8 in. or less = 0.1875 times the thickness or 1/16“ – whichever is larger.
- For thickness of 3/8 in. and over = 0.1875 times the thickness or 1/8“ – whichever is smaller.
The procedures, the welding operators as well as all operators shall be qualified under Sec. IX, part A, of the ASME Boiler and Pressure Vessel Code, or under AWS B2.1, or under any other code mutually agreed on between purchaser and manufacturer.
Production weld tests
The production weld tests consists of: a two bend-test (interior and exterior bends), two reduced-section tension tests and a macroetch test.
The frequency of production weld tests : There shall be at least one set of weld-test specimens taken of each size, grade, and wall thickness from work performed by each production machine and each operator at a minimum of every 3000 ft. of pipe.
Each length of pipe shall be tested by the manufacturer to a hydrostatic pressure not less than that determined by the following formula : P= 2St/D
P = minimum hydrostatic test pressure (psi).
Note: By agreement between the purchaser and the manufacturer, when the diameter and the wall thickness of the pipe are such that the capacity of the testing equipment is exceeded by these requirements, the test pressures may be reduced or other non destructive test methods may be used.
S = stress in pipe wall during hydrostatic test which shall be 0.75 times the specified minimum yield point of the steel used, or as specified by the purchaser.
T = wall thickness (in.)
D =outside diameter (in).
The test pressure shall be held for sufficient time to observe the weld seams. There shall be no leaks.
Thickness and weight
Unless specified by the purchaser, the wall thickness and weight tolerances for welded pipe shall be governed by the requirements of the specifications to which the plates or sheets are ordered.
The pipe shall be substantially round. The outside circumference of the pipe shall not vary more than +/- 1%, but not to exceed ¾“ from the nominal outside circumference based on the nominal diameter.
Finished pipe shall not deviate by more than 1/8 in. from a 10-ft. long straightedge held against the pipe.
Specified pipe lengths on the order shall be furnished with a tolerance of +/- 2 “.
Preparation of ends
If pipe is specified to have the ends bevelled for field butt welding, the ends shall be beveled to an angle of 300 with a tolerance of +50 , -00 with a width of root face of 1/16” +/- 1/32”.
Ends fitted with flanges
Ends to be fitted with flanges shall be grinded (longitudinal and spiral welds), at ground flush for a sufficient distance to allow proper installation of the flange.
The out-of-roundness of pipe ends shall be consistent with the diameter and wall thickness. Any out-of-roundness shall be limited to a smooth oval that may be jacked back to a circular shape.
The tolerance on the diameter of the ends is of – 1/16“ and more than 1/8“ of the specified diameter.
-1/16“ is equal to -0.196“ on the circumference and +1/8“ is equal to +0.393“ on the circumference.
Squareness of ends
For pipe that is to be butt-welded in the field, the ends of pipe sections shall not vary by more than 1/8 in. at any point from a true plane perpendicular to the axis of the pipe and passing through the center of the pipe at the end.
By agreement between the manufacturer and the purchaser, the ends of the pipe may be supplied with joint configurations and tolerances other than those described herein. In such cases, pipe ends shall conform to the description of detail drawings provided by the purchaser.
A serial number or other identification shall be painted in a conspicuous location on each section of pipe and each special section.