2.1 Welding Procedure Specification (WPS) Requirements & Contents
Key Takeaways
- API 1104 Section 5.1 mandates that a detailed written WPS be established and qualified before any production welding begins; acceptance of the qualification weld is by destructive testing per 5.6 or 5.8.
- Section 5.3.2 lists nineteen specification items: process, materials (SMYS range), diameters/wall thicknesses, joint design, filler metal and bead sequence, electrical characteristics, flame characteristics, position, direction, time between passes, lineup clamp, cleaning, preheat/interpass, shielding gas, shielding flux, travel speed, cooling method, postheat, and PWHT.
- Section 5.3.2.10 requires the WPS to specify the maximum time between completion of the root bead and start of the second bead (and second to third bead) when EXX10 or EXX11 cellulosic electrodes are used.
- Section 5.3.2.11 requires the WPS to state whether the lineup clamp is internal or external and the minimum percentage of the root bead that must be completed before clamp release — the percentage itself is a WPS variable, not a fixed code number.
- The procedure qualification record (5.2) documents the actual observed values of all 5.3 variables plus complete test results, and must be maintained as long as the procedure is in use.
2.1 Welding Procedure Specification (WPS) Requirements & Contents
In pipeline construction governed by API Standard 1104 (22nd Edition), Section 5.1 requires that before any production welding starts, a detailed Welding Procedure Specification (WPS) be established and qualified to demonstrate that sound welds with suitable mechanical properties (strength, ductility, hardness) can be made by the procedure. Acceptance of the procedure qualification weld is determined by destructive testing per 5.6 (butt welds) or 5.8 (branch and fillet welds). Section 5 applies to manual and semiautomatic welding with filler metal; mechanized welding procedures are qualified under Section 12.
The procedure qualification record (5.2) is the evidence file: it must document the actual observed values for every variable specified per 5.3 plus the complete qualification test results, and it must be maintained for as long as the procedure is in use. Multiple qualification welds may be combined to qualify a range of essential variables within one WPS.
The Nineteen WPS Contents Items (Section 5.3.2.1-5.3.2.19)
An API 1104 WPS must address every applicable item of 5.3.2. Omission of a required field makes the document non-compliant.
| Item | Subsection | What the WPS Must Specify |
|---|---|---|
| Process | 5.3.2.1 | Specific process or combination (SMAW, GMAW, FCAW, GTAW, SAW, PAW, OFW) and method of application (manual or semiautomatic) |
| Materials | 5.3.2.2 | SMYS range of the materials to which the procedure applies |
| Diameters & wall thicknesses | 5.3.2.3 | Ranges of specified outside diameters and wall thicknesses |
| Joint design & weld shape | 5.3.2.4 | Sketch with tolerances for bevel angle, root face, root opening; cap height/width tolerances; fillet shape/size; backing type if used |
| Filler metal, flux & beads | 5.3.2.5 | Sizes and classification of filler metal and flux; minimum number and sequence of beads (designated per company-defined thickness subsets where they differ) |
| Electrical characteristics | 5.3.2.6 | Current and polarity; voltage and amperage ranges for each electrode type/size; heat input and its calculation method when Table 1 requires it |
| Flame characteristics | 5.3.2.7 | For oxy-fuel: neutral, carburizing, or oxidizing flame; torch tip orifice size per rod/wire size |
| Position | 5.3.2.8 | Roll or fixed position welding |
| Direction of welding | 5.3.2.9 | Vertical up, vertical down, or horizontal |
| Time between passes | 5.3.2.10 | With EXX10/EXX11 electrodes: maximum time from root bead completion to start of second bead, and from second to third bead (minutes or hours) |
| Lineup clamp | 5.3.2.11 | Internal or external clamp (or none); if a clamp is used, the minimum percentage of the root bead to be completed before release |
| Cleaning/grinding | 5.3.2.12 | Power tools, hand tools, or both |
| Preheat & interpass | 5.3.2.13 | Heating method, minimum preheat, and maximum interpass temperature |
| Shielding gas & flow | 5.3.2.14 | Gas classification and flow-rate range |
| Shielding flux | 5.3.2.15 | Type of shielding flux, when applicable |
| Speed of travel | 5.3.2.16 | Travel-speed range for each pass or pass grouping |
| Cooling after welding | 5.3.2.17 | Type of deliberate cooling (if any) and maximum weld temperature before cooling |
| Postheat | 5.3.2.18 | Minimum temperature and time for hydrogen-diffusion postheating, when used |
| PWHT | 5.3.2.19 | Full PWHT procedure: application method, heating rate, temperature range, time at temperature, cooling rate |
The Two Administrative Rules Candidates Confuse
Time between passes (5.3.2.10). The requirement to put maximum root-to-second-bead and second-to-third-bead times in the WPS applies specifically to EXX10 and EXX11 (cellulosic) electrodes. Cellulosic root beads carry high diffusible hydrogen and see heavy restraint; a fast hot pass tempers the root and drives hydrogen out. The WPS states the limits in minutes or hours — the standard deliberately does not print a universal number.
Lineup clamp removal (5.3.2.11 + 7.3). The WPS states whether the clamp is internal or external and the minimum root-bead percentage that must be complete before release. Section 7.3 adds that when a clamp is removed before root-bead completion, the completed part of the bead shall be in approximately equal segments spaced approximately equally around the circumference. Again, no fixed percentage (such as "50%") appears in the standard — it is a qualified WPS value.
Qualifying the WPS
To qualify the WPS, a test joint of two pipe nipples is welded following every detail of the draft procedure (5.5). The recorded variables go into the qualification record; the coupon then goes to visual examination and the destructive tests of 5.6 (tensile, nick-break, root/face/side bends as required by Table 3). Only when every specimen meets the acceptance requirements of 5.6 — or the branch/fillet requirements of 5.8 — is the procedure qualified for production.
Under API 1104 Section 5.3.2.10, the WPS must specify the maximum time between completion of the root bead and start of the second bead when which electrode family is used?
According to API 1104 Sections 5.3.2.11 and 7.3, what controls the release of a lineup clamp before the root bead is complete?
Which document records the actual variables observed during welding of the procedure qualification test joint along with the complete mechanical test results?