BS 1640-3:1968(1999) Specification for Steel butt - welding pipe fittings — For the petroleum industry — Part 3 : Wrought carbon and ferritic alloy steel fittings — Metric units
2007BS EN 10253-2:2007 Butt-welding pipe fittings - Non alloy and ferritic alloy steels with specific inspection requirements
1968BS 1640-3:1968 Specification for steel butt-welding pipe fittings for the petroleum industry - Wrought carbon and ferritic alloy steel fittings - Metric units