API 1169 Welding, Coating & Installation Construction

Welding: procedure, welder, production weld

Two qualifications, never one

API 1104 qualifies two things separately. The welding procedure is qualified once, by welding and destructively testing a test joint, and is then written up as the instructions the crew works to. The welder is qualified separately, by making a test weld under that procedure. A qualified procedure does not qualify the person holding the stinger, and a qualified welder cannot rescue a procedure that was never tested. When a stem describes a change on the line, the first sort is: does it break the procedure or the welder?

A procedure stays valid only while its essential variables stay inside what was qualified; change one and the procedure has to be requalified. A welder's qualification also covers a limited range of joints, so moving the same person to a different job can mean a new test even when the procedure has not changed. The exam likes to offer four changes and ask which one forces requalification: three will be adjustments the procedure already allows, one will cross a line the procedure section draws.

Recency: the gas and liquid rules are not the same sentence

Under 49 CFR 192.229 a gas welder must have welded with the process within the preceding six calendar months, and on higher-stress pipe the rule adds a tested weld, with an alternative of two tests a year no more than 7½ months apart. Under 49 CFR 195.222 a liquid welder needs both in the preceding six calendar months: welding with the process and one weld tested and found acceptable. Options that differ only by "and had one weld tested" are testing exactly this split.

What you watch at the line

1. 1+00

   Before the arc

   The procedure and the welder's qualification are on file for this joint; pipe ends are inspected, bevels are clean and undamaged, and the fit-up matches the procedure. Heat numbers and joint numbers match the pipe tally.

2. 2+00

   Preheat and weather

   Preheat, if the procedure calls for it, is checked with the method the spec names, and the weather is checked before the arc is struck. What the code says about wind and rain is one of the drill questions below.

3. 3+00

   Root and hot pass

   Line-up clamp removal and the time between passes follow the procedure. Lifting or lowering the joint before the root is far enough along is a classic crack starter.

4. 4+00

   Fill, cap and visual

   Each weld is cleaned between passes, finished, marked with its weld number and the welder's identification, and visually inspected before it goes to NDT.

5. 5+00

   NDT and the weld map

   The weld goes on the weld map and the NDT log. Results come back accepted, repair, or cut out, and each outcome is recorded against the weld number.

Stringing and pipe handling

Stringing questions are about protecting pipe you cannot easily replace and recording what went where. Each joint is laid on padded skids or sandbags, kept off rock, with skips left at roads, driveways and crossings so traffic and livestock can pass. End caps stay on to keep dirt and water out of the bore and protect the bevels. Pipe is handled with end hooks, vacuum lifters or wide slings that do not damage coating; brass-lined hooks are out, because transferred brass can cause cracking when the bevel is later welded.

The pipe tally is the record that carries traceability: joint number, heat number, grade, wall thickness, length and coating, checked against the stencil and the mill test report. Every length is visually inspected at the site under 49 CFR 192.307 or 49 CFR 195.206. Unmarked pipe, or pipe whose stencil does not match the paperwork, is set aside until the question is resolved.

Damage has a hard rule. On higher-stress gas pipe, 49 CFR 192.309 requires removal of a dent deeper than ¼ in on pipe of 12¾ in OD or smaller, or deeper than 2% of the diameter on larger pipe, and of any dent that contains a gouge or sits on a weld. Removal means cutting out a cylinder of pipe. Pounding a dent back out or patching over it is not allowed.

Ditch, depth of cover and clearance

Cover questions are lookups from the on-screen regulations, and the trap is almost never the normal-soil number. Read across the table: the two codes agree on ordinary rural ground and split on rock, which is where the options are built.

Two more numbers travel with cover. Pipe needs at least 12 in of clearance from any other underground structure (192.325, 195.250), with a smaller minimum for drain tile on liquid lines; where 12 in cannot be had, the pipe is protected instead. And under 195.210 a liquid line within 50 ft of a dwelling, industrial building or place of public assembly needs 12 in of extra cover.

Ditching is also an excavation, so the OSHA rules for protective systems, egress and the competent person's daily inspection apply in this category too. Those questions are worded "according to OSHA", and they are covered on the safety, quality and environmental page.

Crossings and HDD, lowering-in, tie-ins

Bores, HDD and road or rail crossings

Crossings are governed first by the crossing permit and the drawings: cased or uncased, wall thickness, depth below the road or rail, and any conditions the road or railroad owner set. On a cased crossing, the casing insulators, end seals and vents go in per drawing, and the carrier pipe must not touch the casing. For bored and drilled installations 192.461 also asks for precautions to limit coating damage, which is why pull sections usually carry an abrasion-resistant overcoat.

On a horizontal directional drill the inspector follows the pilot hole against the planned profile, watches drilling fluid returns and containment, and reports any inadvertent return the way the permit and the project's contingency plan require. The pull section is welded, tested and coated before pullback; after pullback, the exposed end is checked for coating damage.

Lowering-in

Before the pipe moves, the ditch is checked for depth, rock, debris and water, and padding is in place where the spec calls for it. During the lift, sidebooms are spaced and counted per the lift plan, the pipe rides in slings or cradles that do not cut coating, nobody stands under the load, and the string is lowered, not dropped, so it rests on the ditch bottom without being forced into place.

Tie-ins

Tie-ins join sections that were built apart, so they arrive with stress, gaps and cut pieces. The joint is aligned without forcing; cut-offs and new pups are recorded with their heat numbers on the tally; the weld is made to a qualified procedure and gets 100% NDT under both codes. A tie-in bell hole is an excavation, so the same protective-system questions apply.

Questions people ask