Hydraulic Tubes, IBR Boiler Pipes and Square Pipes

IBR stands for the Indian Boiler Regulations, 1950. They were framed under the Boilers Act, 1923, which was replaced by the Boilers Act, 2025 from 1 May 2025. The new Act keeps the existing regulations in force until new ones are notified, so the IBR certification system for pipes and tubes carries on as before.

Under the boiler law, a steam pipe is one carrying steam at more than 3.5 kg/cm² above atmospheric pressure, or a pipe over 254 mm internal diameter carrying steam above 1 kg/cm². Pipes and tubes for boilers and such steam pipes must be made and tested as the Regulations lay down. In practice an "IBR pipe" is a pipe whose manufacture and testing are certified on the prescribed form:

• Form III-A: certificate of manufacture and test for pipes
• Form III-B: certificate of manufacture and test for tubes
• Signed by the maker's competent person and by a well-known pipe or tube maker recognised by the Central Boilers Board, or by an approved Inspecting Authority
• Material traceable by heat number from the certificate to the pipe

An A106 Grade B pipe made for IBR service and one made without IBR can have the same chemistry and strength. The difference is the approval of the maker, the inspection at the mill, and the certificate. That is why IBR status has to be decided before the pipe is made; no amount of testing at site turns an uncertified length into IBR pipe.

Common IBR pipe specifications include A106 Grade B for carbon steel lines and A335 P11 and P22 for hotter steam. Boiler tubes are often ordered to BS 3059 or ASME tube specifications. Seamless and ERW versions both exist; which one is acceptable is fixed by the boiler design and the specification on the approved drawing.

Hydraulic lines on presses, machine tools, earthmovers and test rigs are usually built with tube and compression fittings rather than pipe and welded joints. The fitting's ferrule bites into the tube's outer surface, so the outside diameter must be accurate and the surface free of scratches and scale. That is why hydraulic tube is cold drawn and normalised, and sold by OD and wall in millimetres, such as 12 × 1.5 or 25 × 3.

Hydraulic tube is commonly specified to EN 10305-4, the standard for seamless cold-drawn tubes for hydraulic and pneumatic power systems, or to its older German predecessor DIN 2391. Send us the specification with your enquiry and we confirm what can be supplied. Matching compression fittings with ferrules can go in the same order.

Square and rectangular pipes, more properly called hollow sections, are made by forming strip and welding it by ERW. In India they are commonly bought to IS 4923, the standard for hollow steel sections for structural use. Fabricators use them for machine bases, conveyor frames, gates, trolleys, mezzanine framing and pipe racks, where flat faces make fit-up and bolting much easier than round pipe.

Square pipe is a structural product, not a pressure product. If a square section is going to carry fluid under pressure, talk to your designer first. For angles and channels to go with your square pipe, see our MS structural sections.

For boiler pipe, give the specification, size, schedule, quantity and the words "IBR required". For tube, give OD, wall, length and specification. For square pipe, give the size, wall thickness and length. Sizes are confirmed at enquiry, and every supply goes with a test certificate.