BS 2790:1992

This standard BS 2790:1992 Specification for design and manufacture of shell boilers of welded construction is classified in these ICS categories:

• 27.060.30 Boilers and heat exchangers

1.1.1 This British Standard specifies requirements for the design and the construction, including materials, workmanship, inspection, testing, documentation and marking, of directly fired and waste heat shell boilers. The boilers dealt with are of cylindrical design, either horizontal or vertical, constructed from carbon or carbon manganese steels by fusion welding to class I, class II or class III classifications, for which the limits of application are given in Table 1.1.1.

They are intended for land use to provide steam or hot water. This standard does not apply to water-tube boilers (see BS 1113) nor to boilers of the locomotive type.

Additionally requirements relevant to safe operation are specified for the installation of associated safety valves, fittings, mountings and automatic control equipment.

Table 1.1.1 — Limits of application

Classification	Limits of application
Class I	If either or both of the following apply: design pressure > 0.725 N/mm2 design pressure (in N/mm2) multiplied by the mean diameter of the boiler shell in millimetres > 920
Class II	If neither of the following limits apply: design pressure > 0.725 N/mm2 design pressure (in N/mm2) multiplied by the mean diameter of the boiler shell in millimetres > 920
Class III	If neither of the following limits apply: design pressure > 0.38 N/mm2 design pressure (in N/mm2) multiplied by the mean diameter of the boiler shell in millimetres > 480

1.1.2 In addition to the definitive requirements, this standard also requires the items detailed in 1.7 to be documented. For compliance with this standard, both the definitive requirements and the documented items have to be satisfied.

1.1.3 Design and construction of superheaters, economizers, air pre-heaters, mechanical stokers, gas or oil-burning equipment, forced or induced draught equipment or other ancillary equipment which may be required by the purchaser are not within the scope of this standard and are matters for mutual arrangement between the purchaser and the manufacturer. For specifications for such ancillary equipment, reference should be made to the appropriate British Standard (e.g. BS 1113 for superheaters, BS 759-1 and BS 6759-1 for boiler mountings).

1.1.4 This standard does not cover the design and construction of brickwork setting, insulation, furnace fittings or the design of boiler mountings.

1.1.5 Requirements for the repair or modification of in-service boilers are outside the scope of this standard.

Materials, determination of design temperature of components, calculation of scantlings, compensation of openings, design of supports, manufacturing procedures, tolerances, welding, inspection, non-destructive testing for 3 classes of boiler and pressure testing. Additional information and design and manufacturing considerations details in appendices.