Stud bolts and nuts

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The main function of a stud bolt is to deform the gasket placed in the flanged joint avoiding fluid leakage to the outside both in installation and in operation, it must be strong enough to resist the additional loads caused in service by the different variables: pressure, temperature and number of cycles.

ASTM A 193

Standard specification for studs of alloy steels and stainless steels for high temperature or high service pressures and special applications.

The ASTM standard includes fasteners intended for use in pressure vessels, valves, flanges and fittings. Although this material is often available in current unified national thread (UNC) pitches, if used in traditional applications, threads are specified 8 threads per inch (8UN) for diameters greater than one inch.

The following is a basic summary of some of the common grades.

B7 and B7M: Must be heat treated by quenching in a liquid medium and tempered. For B and BM fit components, such as screws, bolts or studs, the heat treatment (which may be the quench operation if performed at 1150ºF (620ºC) minimum), shall be performed after all machining and forming operations. Surface preparation for hardness testing, non-destructive evaluation or ultrasonic elongation measurement on studs is permitted. For grade B7M the maximum hardness shall be 235 HBW or 99 HRB and the minimum hardness shall be 200 HBW or 93 HRB.



ASTM A 194

Standard specification for nuts in carbon steel, alloy steels and stainless steels for high temperature or high pressure service and special applications.

ASTM A194 specification covers carbon steel, alloy steel and stainless steel nuts intended for use in high pressure and/or high temperature service. Unless otherwise specified, the standard heavy series sized under the parameters of ASME/ANSI B and ASME/ANSI B 1.1 shall be used. Nuts up to D.N 1″ shall be UNC Series 2B. Nuts larger than D.N 1″ shall be type 8UN Series 2B.


We are exclusive representatives in Colombia of LAMONS for cutting and supply of asparagus and nuts. We have a large stock of ASTM A 193 B7 and B8 studs, and ASTM A 194 GRADE 2H and GR8 nuts with diameters from 5/8″ to 3″ ready to be installed between ASME B 16.5, ASME B 16.47 and API 6A flanges. The studs are cut with typical 1/8″ bevel on both ends to facilitate installation of the nuts on the stud.

Special materials of asparagus in ASTM B7M, B16, B8M and nuts in ASTM A 194 grade 2HM 4,7 and 8M among others, are imported from LAMONS with excellent delivery times.

We have specialized machinery and equipment for the supply of asparagus and nuts in any diameter and material, which allows us to attend emergencies 24 hours a day, 7 days a week.

Stud bolts and nuts

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