Quiz- Section 13 Automatic Welding Without Filler Metal Additions- CWI Part C -10 Questions
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Section 13: Automatic Welding Without Filler Metal Additions
13.1 Acceptable Processes
Section 1 3 addresses the welding of pipe using automatic welding without filler metal additions. It applies to only one welding process: the fash butt welding process.
13.2 Procedure Qualification
Subsection 1 3.2 requires at least two test welds to be made, followed by radiographic testing prior to destructive testing using tension, nick break, and side bend tests. If the required tests are acceptable, the welding variables at which these two test welds are made will establish the maximum and minimum values permitted for welding voltage, welding current, axial speed, time intervals in the weld cycle, and upset stroke on the resulting welding procedure.
Table 1 0 on page 75 lists the type and number of test specimens required for procedure qualification. The number of specimens depends on the outside diameter of the pipe, with a larger diameter pipe requiring more specimens, as shown in Figures 30, 31, and 32 on pages 73 and 74.
Paragraph 1 220.127.116.11 addresses the tension tests required. The preparation, testing, and acceptance criteria are the same as previously described in Section 5.
Paragraph 1 18.104.22.168 addresses the nick break tests required. Since fash butt welding is typically used on large diameter, heavy-wall pipe, wider nick break specimens are used. These are 2-inches wide as opposed to the 1 -inch wide specimens required in Sections 5 and 1 2. Figure 33 on page 76 shows a schematic of these 2-inch wide specimens. These specimens have, in addition to the 1 /8-inch deep notch on each edge of the specimen, a 1 /1 6 inch, max. , the deep notch on the top and bottom of the weld bead. In order to locate the notch on the bond line, however, the edges of the nick break specimen must be polished and macro etched to reveal the bond line.
Other than that, the preparation and testing for nick break tests are the same as previously described in Section 5. The acceptance criteria, however, are slightly different from those required in Section 5. Paragraph 1 22.214.171.124 addresses the side bend tests required. Since fash butt welding is typically used on large diameter, heavy-wall (greater than ½ inch thick) pipe, no face and root bend tests are used – only side bend tests. The preparation, testing, and acceptance criteria are the same as previously described for side bend tests in Section 5.
The details of each procedure shall include all of the data specified in subsection 1 3.4. The record of the qualification shall show the results of the qualification tests and shall be retained as long as the procedure is in use.
13.4 Welding Procedure Specification
This paragraph lists the variables required to be recorded on a welding procedure specification. Theyare:
(a) The welding process.
(b) The pipe material.
(c) The pipe wall thickness and OD.
(d) The preparation of the pipe, grinding of the pipe seam, and cleaning of the pipe ends.
(e) The welding position.
(g) Cleaning and inspection of electrical contact shoes.
(h) Permitted range of welding voltage.
(i) Permitted range of welding current.
(j) Permitted range of axial speed.
(k) Permitted range of time intervals in the weld cycle.
(l) Permitted range of upset stroke.
(m) Time delay before the removal of clamps.
(n) Method of removing internal fash.
(o) Method of removing external fash.
(p) PWHT time, temperature, measurement techniques, and cooling rate requirements.
13.5 Essential Variables
This paragraph lists the essential variables for the qualification of welding procedure specifications. They are:
(a) A change in the pipe material.
(b) A change in the specified pipe wall thickness or OD.
(c) A change in the pipe preparation dimensions.
(d) A change in the welding position.
(e) A change in the requirements for preheating.
(f) A change in voltage to a value outside the range listed on the welding procedure specification.
(g) A change in current to a value outside the range listed on the welding procedure specification.
(h) A change in the axial speed to a value outside the range listed on the welding procedure specification.
(i) A change in the time intervals in the weld cycle to a value outside the range listed on the welding procedure specification.
(j) A change in the upset stroke distance to a value outside the range listed on the welding procedure specification.
(k) A change in PWHT conditions.
13.6 Qualification of Equipment and Operators
Each welding operator must qualify by welding a test coupon that meets all of the test requirements imposed by subsection 1 3.2, in other words, the same tests as required for qualifying a welding procedure.
13.7 Records of Qualified Operators
A record shall be made of the tests and results required by subsection 1 3.6. A form similar to that shown in Figure 2 on page 1 1 should be used, but any form is suitable as long as it records all of the required information. A list of qualified operators and the procedures for which they are qualified shall be maintained. An operator may be required to requalify if a question arises about his competence.
13.8 Quality Assurance of Production Welds
The company has the right to inspect all welds using nondestructive means, by removing welds and subjecting them to destructive tests, or both. The frequency of any of these tests shall be at the discretion of the company.
Paragraph 1 3.8.2 states that production welds can be rejected if the welding voltage, current, axial speed, cycle time, or upset stroke variables recorded during the weld are outside the ranges specified in the welding procedure specification. Welds can be rejected either during the welding process or after welding has been completed. Rejected welds must be removed from the line.
Paragraph 1 3.8.3 states that production welds can also be rejected based on the results of nondestructive testing, including visual examination, in accordance with the requirements of subsection 1 3.9.
Paragraph 1 3.8.4 establishes limits for internal and external reinforcement. Internal (ID) reinforcement shall not exceed 1 /1 6 inches and outside (OD) reinforcement shall not exceed 1 /8 inches. Values in excess of these require rejection of the weld; however, if it is possible to remove the fash from the weld initially, it should also be possible to remove any reinforcement in excess of these limits to render the weld acceptable.
Paragraph 1 3.8.5 requires each fash butt weld to be subjected to an austenitizing heat treatment, meaning PWHT at a temperature above the upper transformation temperature, also referred to as the Ac3. This is the temperature above which the ferrite-to-austenite transformation is complete. This heat treatment must be followed by controlled cooling or still-air cooling. Any deviation in time at temperature, maximum temperature, or cooling rate beyond those specified in the welding procedure specification shall require reheat treatment.
13.9 Acceptance Standards for NDT
Paragraph 1 3.9.1 states that the acceptance criteria in paragraph 1 3.9.2 apply to flaws found by radiography or by any other nondestructive test method, including visual examination. Paragraph 1 3.9.2 establishes limits for isolated slag inclusion (ISIs) and allows a small amount. However, cracks, incomplete fusion, and porosity in a fash butt weld are all causes for rejection, regardless of size or length.
13.1 0 Repair and Removal of Defects
Subsection 1 3.1 0 establishes the rules for the repair and removal of defects. Paragraph 1 3.1 0.1 states that defects that are open to the surface may be repaired by grinding if the pipe’s minimum wall is not violated. Other defects may be removed by grinding, chipping, or gouging (or a combination of these), followed by a repair weld in accordance with Section 1 0. All repair welds must be approved by the company.
Paragraph 1 3.1 0.2 states that porosity found in a fash butt weld cannot be repaired; therefore, a fash butt weld containing porosity is rejected and must be removed from the line. However, porosity found in a repaired area (welded with a different process) of a fash butt weld shall be acceptable if it does not exceed the limits established in paragraphs 126.96.36.199 for individual or scattered porosity or 188.8.131.52 for cluster porosity.
13.1 1 Radiographic Procedure
Subsection 1 3.1 1 states that radiography of fash butt welds shall be performed in accordance with the rules described in subsection 1 1 .1.