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This Standard specifies the general requirements for bolting for flanges and pressure containing
purposes, and gives details of dimensions for metric and inch series fo bolting.
Materials have been selected for use at temperatures over the range -250°C to 750°C. Information to be
supplied by the purchaser is given in appendix C.
For the purposes of this British Standard, the Following definitions apply.
1.2.1 General terms.
1.2.1.1 bolt
A fastener with a head intergral with the shank and which is threaded at the opposite
end.
1.2.1.2 studbolt
A fastener threaded at both ends, or threaded for the whole of its length.
1.2.1.3 stud
A fastener threaded at both ends, one end of which is screwed into the parent metal and the other end of
which takes a nut.
1.2.1.4 bolting
Bolts, threaded studbolts and studs made to the designs show in figures 1 and 2(for metric series bolting)
and figures 4 and 5 (for inch series bolting).
NOTE. The Term bolting also refers to nuts.
1.2.2 Terms relavant to studbolts
1.2.2.1 nominal length
(a) Of metric series bolting. The length of a studbolts including the point at each end.
(b) Of inch series bolting. The length of a studbolt excluding the point at each end.
1.2.2.2 length of thread
(a)Of metric seires bolting. The distance from the end of a studbolts, including the point, to the last
full thread.
(b)Of icnh series bolting. The distance from the end of a studbolt, excluding the point, to the lead full
thread.
1.2.2.3 length of reduced diameter portion
The distance from the end of the thread to the end of the adjacent plain portion.
1.2.2.4 length of thread plus length of reduced diameter portion
(a) Of metric series bolting. The distance from the end of a studbolt, including the point, to the end of
the reduced diameter adjacent to the plain portion.
(b)Of inch series bolting. The distance from the end of a studbolt, excluding the point, to the end of the
reduced diameter adjacent to the plain portion.
1.2.2.5 length of point
The distance from the end of a studbolt to the position where the approximate 90° point meets the nomial
diameter.
Bolts, studbolts and studs shall be manufactured from the materials specified in tables 1, 2 and 3
NOTE 1. Bolting made from low or medium carbon steels should not be used at temperatures above 300 °C.
This limit applies to bolts of grades 4.8, 6.8 and 8.8 of BS 6104: Part 1 or BS 3692 and the equivalent
Imperial grades, respectively grades B, P and S of BS 1768 and bolts to BS 1769.
Service above 300 °C could result in significant, permanent reduction in the strength of the bolting. If
the temperature is likely to exceed 300 °C the purchaser should seek guidance from the manufacturer about
the steel to be used for the bolting.
NOTE 2. Austenitic stainless steels are available in both the solution treated and the higher strength,
cold worked and warm worked conditions.
Threading Method
Threads shall be rolled, machine cut or ground.
NOTE. The purchaser should indicate at the time of enquiry and order if a particular method is to be used
(see appendix C).
Heat Treatment
Materials shall be heat-treated in accordance with the relevant clause of the material standards and as
given in tables 1 and 2. For sour gas applications the final heat treatment process shall be carried out
after all machining or forming operations have been completed on all ferritic and austenitic steels, in
order to remove all hardening effects of cold work.
Check Analysis
If a check chemical analysis from samples representing the materials of the bolting is made, the chemical composition thus determined shall be in accordance with the requirements of the relevant material specified (see tables 1, 2 and 3).
NOTE. Where the purchaser requires a check chemical analysis, this should be stated at the time of enquiry and order (see appendix C).
Marking
For bolts, studbolts or studs M16 and larger, or 5% in and larger, symbols identifying the grade of bolt
and the manufacturer shall be applied to one end of the studbolt, on the head of the bolt, or on the nut
end of the stud.
For bolts, studbolts or studs M10 and M12 or 1½ in, symbols identifying the grade of bolt shall be applied
to one end of the studbolt, on the head of the bolt, or on the nut end of the stud.
The identifying marking symbol shall be as shown for the respective grades in table 4.
Metric bolts, studbolts and studs shall have the prefix M in the grade numbers, e.g. MB7, MB7M.
The marking shall be clearly legible with symbols evenly spaced and the symbols shall, where possible, be
not less than 3 mm (1/8 in) high for all sizes of bolting.
Marking by electrolytic etching shall not be permitted.
General
Nuts for bolts, studbolts and studs shall bve manufactured from the materials given in tables 3 and 4.
Manufacturing process
Nuts shall be made by hot forging, cold forging or by machining from the bar.
Heat Treatment
All nuts (except mild or carbon steel nuts, see table 3) shall be heat treated or machined from heat-treated bar as in table 4. Where nuts are machined from bar heat treated in accordance with those requirements, the nuts shall not require further heat treatment. For sour gas applications, the final heat treatment process shall be carried out after all machining or forming operations have been completed on all ferritic and austenitic steels, in order to remove all hardening effects of cold work.
Check analysis
If a check chemical analysis from samples representing the nuts is made, the chemical composition thus determined shall be in accordance with the relevant material standard (see table 4).
Marking
Nuts shall be marked on one end face (not the bearing face) or on one flat, to indicate the grade of nut and the manufacturer. The identifying marking symbol shall be as shown for the respective grades in table 4.
Metric nuts shall have the prefix M in the grade numbers, e.g. M2H, M2HM.
The marking shall be clearly legible with symbols evenly spaced. These symbols where practicable shall be not less than 3 mm (1/8 in) high for all sizes of nuts.
Marking by electrolytic etching shall not be permitted.