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发表于 2019-10-12 21:08:39
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API对API 1104的5.3.2.16条款有解释：
Background: Section 5 of API-1104 20th Edition states that before any production welding is started, a detailed procedure specification shall be established and qualified to demonstrate that welds with suitable mechanical properties (such as strength, ductility, and hardness) and soundness can be made by the procedure.
For the WPS, Section 5, 5.3.2.16 (Speed of Travel) requires the range for speed of travel, in inches per minute be specified for each pass. Section 5, 5.4 lists essential variables and states in 5.4.1 (General) a welding procedure must be re-established as a new procedure specification and must be completely re-qualified when any of the essential variables listed in 5.4.2 are changed. Final WPS written with Travel Speeds being more restrictive than those qualified during Procedure Qualification.
During procedure qualification, a travel speed range was established from 3 to 10 inches per minute. The WPS was written with a more restrictive specified Travel Speed range of 7 to 10 inches per minute. The WPS was written with tighter Travel Speed ranges for heat input control. In each welding pass, the more restrictive range was always within the wider range established on the PQR.
Question 1: Can the “specified” Travel Speed range listed on the WPS be more restrictive than that recorded in the procedure qualification record, so long as the restricted range is within the range established in the PQR?
Question 2: If the Travel Speed range specified on the WPS is more restrictive than the recorded Travel Speed range established on the PQR, has an essential variable (Speed of Travel) been violated requiring a new WPS be qualified per 5.4.1?
Response 1: Yes, the range listed in the procedure qualification may be narrower than that used on the qualification test.
Response 2: No.
Reasoning: API 1104, Section 5.3.2.16 requires that the Company specify the range of travel speed in the welding procedure specification. API 1104 does not set the welding procedure travel speed range based on the actual range used in the qualification test. The pipe diameter, wall thickness, electrode diameter, travel speed, voltage and amperage are interdependent. The travel speed range actually used on the qualification test may need to be adjusted in the welding procedure specification to account for different pipe diameters, wall thicknesses, electrode sizes etc that are covered by the welding procedure specification.
There are different approaches to welding procedure qualification:
a) The Company may choose to qualify using a “typical” welding speed range and list a wider range in the welding procedure specification to allow for different electrode sizes, voltages and amperages that might be used for different pipe diameters and wall thicknesses.
b) The Company may choose to qualify using a very wide range of travel speed (e.g. explore the usable travel speeds) and then list a tighter range in the welding procedure specification to get more average production welds.
c) The Company may choose to shift just the high end or low end of the travel speed range depending on the Company‟s relative concern for low or high heat input.
d) The Company may choose to write two specifications from a single test weld, one with a wide range and one with a narrow range, to use for specific applications.
All of these approaches to procedure qualification are allowed by API 1104. The Company sets the travel speed range listed in the welding procedure specification as they feel appropriate.
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发表于 2019-10-12 18:36:27
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