What are the standards for seamless steel pipes for boilers?

Low and medium pressure boiler tube length, bending and delivery quality:

The size specifications, outer diameter, wall thickness and theoretical quality of boiler steel pipes should comply with regulations.

Length:

1. Commonly used lengths, the length of hot-rolled, extruded, and hot-expanded steel pipes is 4-12m. The length of cold-rolled and cold-drawn steel pipes is 4-10.5m.
2. The fixed length and double length should be within the normal length range, and the allowable deviation of the total length is +20mm. Each length of the ruler should be reserved with a specified notch margin; if the outer diameter is less than 159mm, 5-10m, and if the outer diameter is greater than 159mm, 10-15mm.

Bending: 1.5mm/m when the wall thickness is less than 15mm, 2.0mm/m when the wall thickness is greater than 15mm, and 3.0mm/m when the outer diameter is greater than 351mm.

Both ends of the boiler tube should be perpendicular to the axis of the steel tube and burrs should be removed.

The out-of-roundness and wall thickness of boiler tubes shall be negotiated between the supplier and the buyer based on the buyer's requirements and shall be specified in the contract. The out-of-roundness and wall thickness of steel pipes of the same cross-section shall not exceed 80% of the outer diameter and wall thickness tolerances respectively.

Low and medium pressure boiler tubes are made of steel ingots or solid tube blanks that are perforated into capillary tubes and then hot rolled, cold rolled or cold drawn. Suitable for manufacturing high-quality carbon structural steel hot-rolled - hot-rolled, hot-extruded, hot-expanded and cold-drawn, cold-rolled seamless steel pipes for various low and medium pressure boilers.

1. Permissible deviations in outer diameter and wall thickness of hot-rolled, hot-extruded and thermally expanded low- and medium-pressure boiler steel pipes:
1) When the outer diameter is less than 159mm, the outer diameter deviation of ordinary grade +-1.0% (minimum +-0.50mm%) and advanced grade +-0.75% (minimum +-0.40mm%)
2) Ordinary grade with outer diameter greater than 159mm +-1.0%, advanced grade +-0.9%.
3) When the wall thickness deviation is less than 20mm, ordinary grade +15%-12.5% (minimum 0.45mm-0.35mm), high-grade +-10% (minimum +-0.30mm).
4) The wall thickness tolerance of thermally expanded steel pipes with an outer diameter greater than 351mm is +-15%.

2. Allowable deviations in outer diameter and wall thickness of cold drawn or cold rolled low and medium pressure boiler tubes:
1) Outer diameter 10-30, ordinary grade +-0.4mm, high grade +-0.2mm.
2) The outer diameter is larger than 30-50 for ordinary grade +-0.45mm and high-grade +-0.25mm.
3) Ordinary grade with outer diameter greater than 50mm +-1.0%, advanced grade +-0.75%.
4) Wall thickness deviation 1.5-3.0 allows +15%-10%, advanced +-10%.
5) Normal grade with thickness greater than 3.0 +12.5%-10%, advanced grade +-10%