BS 1873 vs API 623: globe valve standards compared

BS 1873 is the British Standard for steel globe valves in petroleum service, and it covers globe stop and check valves in the same document. BSI's published scope puts the envelope at 15 mm to 400 mm and Classes 150 to 2500, in three body patterns, with an outside screw and yoke stem. It is a design standard, so what it settles is construction rather than duty.

BSI's own record for BS 1873:1975 sets the envelope out: cast or forged carbon and alloy steel globe and globe stop and check valves, outside screw and yoke, in straight, angle and oblique Y patterns, with flanged or butt-welding ends.

BSI shows BS 1873:1975 as Current, published 30 April 1975. Its scope also records two extensions worth knowing before a small or awkward line item is written. BSI notes that the standard can serve as a general guide where the material composition falls outside its own materials section, as it does for highly corrosive service or for low temperatures, and that it can be adapted to needle-type seats at 15 mm and 20 mm, with the seat bore reduced and the needlepoint either integral with the stem or loose on it.

That second line matters for a small-bore requisition. BS 1873 reaches 15 mm and carries a stated route to needle seats, while API 623 does not reach that far down at all. The three body patterns BS 1873 names are the same three the globe valve product sheet sets out, which that sheet calls tee, wye and angle for the same bodies, and the outside screw and yoke stem BS 1873 requires works the way the OS&Y memo describes on gate valves.

The two published scopes differ at both ends of the size range and in what they assume about the service. BS 1873 runs 15 mm to 400 mm, API 623 from NPS 2 to NPS 24, so an NPS 20 globe valve falls outside BS 1873 just as a 15 mm one falls outside API 623. Both stop at Class 2500 and both cover stop-check valves.

The comparison below is drawn from BSI's record for BS 1873:1975 and the API Std 623 scope record published by Accuris.

Two things the scope records do not show are on the record in the trade press. In Valve World, Merrick and Casteel describe API 623's starting point as the structure of API 600 combined with the technical content of BS 1873, which they call the most widely used existing specification for process globe valves, so the two documents are related rather than independent. And in the Valve Manufacturers Association's Valve Magazine, Javier Vergara reported, writing when the standard was new in 2014, that the minimum wall thickness in it mirrors API 600 and is greater than ASME B16.34.

Below NPS 2 there is no API 623 valve to quote, and that is the gap a requisition falls into when the size is written before the standard. The same divide runs through the gate valve side, where API 600 and API 602 split the range between bolted-bonnet and compact designs.

Not on its own. The face-to-face figures a pipe fitter works from are tabulated in ASME B16.10, and in the Class 150 table as Wermac reproduces it a globe valve needs a markedly longer gap than the gate valve of the same size. Naming BS 1873 or API 623 settles how the valve is built, not how much pipe it occupies.

Two readings follow for a purchase order. Changing valve type is a piping change, not a like-for-like swap. Either way the length comes from the B16.10 table for that valve type, body pattern, size, class and end connection, so the enquiry has to state the pattern. Gate valve versus globe valve compares the two types on duty rather than on length.

The ASME B16.10 memo covers the tables, the tolerances and the facings.

The questions that follow are the ones a published scope can answer and a product catalogue usually cannot. They all turn on the same axis: BS 1873 is broader on material scope and reaches down to 15 mm, while API 623 is the heavy-wall refinery series. Two enquiry problems sit there, a size outside one of the two envelopes, or a valve that is not a plain globe valve at all.

Can one globe valve be marked to both BS 1873 and API 623?

Where a valve is offered dual-marked, inside the overlap that is possible: the two envelopes meet between NPS 2 (DN 50) and 400 mm, in Classes 150 to 2500. What an enquiry should pin down is which standard the test certificate and the nameplate will name, and to which edition, because that is what a project specification is checked against at goods-in.

Which standard covers a globe valve below NPS 2?

Not API 623: its published scope starts at NPS 2. BS 1873 reaches down to 15 mm, and BSI records that it can be adapted to needle-type seats at 15 mm and 20 mm with a reduced seat bore. The compact route is API Standard 602, whose published tenth-edition scope covers gate, globe and check valves in eleven sizes from DN 8 to DN 100, or NPS 1/4 to NPS 4.

Which edition of each standard applies?

The edition your purchase order names. BSI shows BS 1873:1975, published 30 April 1975, as Current. API Std 623 is in its second edition of January 2021, including Errata 1 from 2024, and replaced a first edition from September 2013, so an older specification may be describing a different document.

A globe valve enquiry that names the standard, the edition, whether it is a stop-check, and the service temperature can be quoted without a round of questions. Send it through the contact page, and see how ordering works for what follows.