Piping inspection and supervision, explained from scratch

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Piping

Spool handling and temporary support — the hours between landed and supported

The period in which a spool has been released by the crane but does not yet have the supports it was designed to have, why that state has no design behind it, what has to be established before the hook comes off, and why Friday afternoon is when pipe ends up on the floor.

IntermediateOil & GasPetrochemicalInfrastructure & Buildings

Standards referencedASME B30.9ASME B30.26EN 12811-1

Most of what is written about pipe supports describes the finished condition — the shoe, the guide, the anchor, the spring, each selected for a load case and drawn on a support drawing. That is the subject of support design and it assumes something that is not true during construction.

A length of large-bore pipe resting on temporary steel props standing on a beam rather than on its permanent supports, with a chain wrapped around the pipe and the adjacent structure, photographed at dusk with nobody present and long shadows across the gravel.
Props, a chain, and nobody on site. This is the condition no drawing covers, photographed at the hour it is usually left in.

It assumes all the supports are there.

Between the moment a spool is landed and the moment its supports are fitted, the line is in a condition nobody designed. The support scheme does not cover it, because the support scheme describes the completed system. The lift plan does not cover it either, because the lift plan ends when the load is set down. The gap belongs to the supervisor.

Four states of a spool shown on a timeline. Slung from the crane; landed at one end with the crane still holding the other; the crane released with one permanent support and whatever else was provided; and finally fully supported as designed. The third state is shaded as the exposed period, because the permanent support scheme assumes all supports are fitted and the lift plan assumes the crane is attached.
Two complete conditions with design behind them, and one in between with none. The third state is where pipe is lost.

Three questions before the hook comes off

Not a procedure, a habit. They take about thirty seconds and they are the difference between a considered arrangement and an assumption.

What is carrying the weight? Which supports are actually fitted, and are they finished? Fitted and complete are not the same thing. A shoe positioned but not welded will carry vertical load perfectly well. A clamp with the bolts in finger tight looks identical to one that is done up.

What is stopping it moving? Weight is rarely what drops a spool. Movement is. A round section sitting on a flat beam will roll given a nudge, a gust, or somebody leaning a ladder on it. A spool with an offset leg is not simply heavy — it is carrying a turning moment and is actively trying to rotate.

For how long? An arrangement you are standing beside for an hour is a different proposition from the same arrangement at five o’clock on a Friday.

Centre of gravity is not the middle

The single most useful habit in handling spools is to stop assuming the centre of gravity is halfway along.

It is halfway along for a straight run of constant bore. Almost nothing else is a straight run of constant bore. A long-radius elbow at one end, a valve, a flange pair, a reducer — each moves the centre of gravity, and the effect is larger than people expect because the heavy items are usually at the ends rather than distributed.

This matters twice. Once while slinging, where a misjudged centre of gravity makes the spool tilt as it leaves the stand. And once while supporting, where it decides whether the spool is stable on the supports that happen to be fitted.

Handling before the lift

Damage done on the ground is paid for at height.

  • Bevels. A machined weld preparation is the most easily damaged part of a spool and the most expensive to repair in position. Protect it, and do not let a spool be dragged on its ends.
  • Flange faces. Same argument. A covered face stays usable.
  • Slinging points. Round slings on painted pipe, not chain. Softeners at edges. Nothing passed through a branch or a flange bolt hole.
  • Stacking. Spools stacked without dunnage deform small bore and damage coating, and the one at the bottom is always the one needed first.

None of this is sophisticated. It is simply the part of the job where carelessness is cheap at the moment it happens and expensive three weeks later.

When to ask for help

Most temporary arrangements are obvious to an experienced supervisor and need no calculation. Some are not, and the ones that are not share features worth recognising:

Feature Why it needs checking
Long unsupported spans Deflection and the stress it induces, not just stability
Loading onto structure not designed for it Temporary load on a platform, handrail or grating
Spools that must stand for an extended period Wind, thermal movement, other trades working nearby
Anything supported off scaffold Scaffolds are designed for access loads, not pipe loads

That last one deserves emphasis. A scaffold is designed for a duty, with a load class behind it under EN 12811-1, and that duty is people, tools and a modest quantity of materials. It is not designed to hold pipework, and using it that way is a genuinely common way to overload one without anybody intending to.

Check your understanding

6 questions. Nothing is recorded — this is just for you.

1Why is the period just after the crane is released the most exposed state a spool passes through?
2A spool is landed on a flat rack beam with one permanent support fitted. What is the first thing that has to be established before releasing the hook?
3Why does the duration of a temporary arrangement change what is acceptable?
4What does it mean to say a support is fitted but not complete?
5Which spool geometry most often catches people out when it is released?
6Who is responsible for deciding the temporary support arrangement during erection?

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