Specifying steel pipe, mesh and sheet

Pipe class and wall thickness

Two separate systems get used interchangeably in this market and they are not the same thing. GI pipe is normally sold by class — light, medium or heavy — which sets the wall thickness for a given bore. Carbon steel pipe is normally sold by schedule, where Schedule 40 and Schedule 80 are the common walls.

• Heavy class GI typically prices 15 to 25 percent above medium class for the same bore, so specifying heavy where medium will do is an avoidable cost.
• Schedule 80 has a thicker wall than Schedule 40 at the same nominal bore, which means a smaller internal diameter — check your flow calculations before switching schedule to gain strength.
• Tell us the bore, the class or schedule, and the finish. If you are unsure, tell us the application and the pressure instead and we will come back with the specification.

Mesh and sheet

• Reinforcement mesh is specified by its reference — A393 and A142 are the common ones. Give us the reference rather than a description and there is nothing to get wrong.
• GI and aluminium sheet are sold by thickness. GI 0.4 mm to 0.7 mm covers most cladding and ducting work; aluminium runs 0.5 mm to 1.0 mm.
• Fencing has moved to its own category. Chain link, welded mesh, palisade and razor wire are on the Perimeter & Security Fencing page, with dimensions and standards against every line.

Which pipe or tube material — before you specify the size

Six products on this page all get called "pipe", and the choice between them is decided by the job, not by price. Getting the material right is the first decision; class, wall and size are the second.

GI pipe class — A, B or C

GI pipe is sold in the UAE by class rather than by schedule, and the class sets the wall thickness. This follows the same light/medium/heavy convention as IS 1239 Part 1, the standard the regional trade still specifies against. The class is NOT a pressure rating — neither IS 1239 Part 1 nor BS EN 10255 assigns one; they fix dimensions and delivery condition, and a working pressure is confirmed on the quotation where the line needs one.

• Medium (Class B) is our stock class and covers most fencing, general structural and water-line work. Heavy (Class C) is priced above it for the same bore, so specifying it where medium will do is an avoidable cost.
• Tell us the bore and the application rather than guessing the class — if you are unsure what pressure or load the line carries, describe the job and we will specify it.

PVC or HDPE for a buried line

Sandwich panels — choosing the core thickness

Core thickness is an insulation decision, not a strength one, and the number that matters is the temperature difference the panel has to hold back — not the building size.

• PIR and PU foam cores perform similarly per millimetre — the choice between them is normally down to fire rating and supplier availability rather than thermal performance.
• Say if the building is Civil Defence-reviewed: the standard combustible PUF core is not what that review wants, and a fire-rated or mineral-wool core needs specifying up front rather than substituted after the drawings are approved.

Matching the anchor to the base

The anchors, screws and bolts on this page are not interchangeable, and the wrong one either fails under load or refuses to fit — usually discovered on site rather than on the drawing.

• Finish follows exposure, not preference: zinc-plated indoors, hot-dip galvanized or 304 stainless outdoors, and 316 stainless near the coast or around chemicals — Ajman's salt air is hard on plain zinc-plated hardware left outside.
• For a genuinely structural fixing — a hoarding post base, a bracket taking real load — tell us the load and the base material and we will size the anchor rather than have you pick a diameter off a shelf.