What is BS 6323-4 standard specification?

 

BSI – BS 6323-4 Specification for seamless and welded steel tubes for automobile, mechanical and general engineering purposes – Specific requirements for cold finished seamless steel tubes

 

This standard is published in eight separate Parts as follows:

—Part 1: General requirements;

—Part 2: Specific requirements for hot finished welded steel tubes;

—Part 3: Specific requirements for hot finished seamless steel tubes;

—Part 4: Specific requirements for cold finished seamless steel tubes;

—Part 5: Specific requirements for electric resistance welded (including induction welded) steel tubes;

—Part 6: Specific requirements for cold finished electric resistance welded (including induction welded) steel tubes;

—Part 7: Specific requirements for submerged arc welded steel tubes;

—Part 8: Specific requirements for longitudinally welded stainless steel tubes.

 

This Part of BS 6323, which is used in conjunction with Part 1 of the same standard, covers the specific requirements for cold finished seamless steel tubes for use in the automobile, mechanical and general engineering industries. It specifies the chemical composition, mechanical properties, dimensions, dimensional tolerances and technical delivery condition of the tubes.

 

General

The tubes shall comply with the general requirements of BS 6323-1 and the specific requirements of this Part of the same standard, which covers tubes up to and including 230 mm outside diameter.

The tubes shall be of steel

grades 3, 3A, 4, 5, 6, 7, 8, 9, 10 and 11. The grade required shall be specified in the enquiry and order, together with other details as specified in clause 5 of BS 6323-1:1982, as appropriate.

If specified in the enquiry and order, tubes having an outside diameter up to and including 50 mm and in the annealed or normalized condition shall be subject to a leak tightness test

 

Method of manufacture

The tubes shall be manufactured by a seamless process and shall be cold finished.

It is permissible for cold finished tubes to have on internal or external surfaces an adherent layer of residual lubricant originating from the drawing process. If phosphate or other residues are detrimental to subsequent processing, then their removal shall be the subject of an agreement between the manufacturer and the purchaser.

 

Delivery condition

1 The tubes shall be supplied in one of the following delivery conditions (see Table 3 in BS 6323-1:1982).

a)Cold finished/hard (cold finished as drawn): BK;

b)Cold finished/soft (lightly cold worked): BKW (see note to 4.2);

c)Annealed: GBK (see 4.2);

d)Annealed (including de-scaling): GZF;

e)Normalized: NBK (see 4.2);

f)Normalized (including de-scaling): NZF.

2 It is permissible for tubes supplied in the GBK and NBK condition to be discoloured, but they shall be free from loose scale.

Where tubes in the GBK condition are required bright annealed, this shall be the subject of an agreement between the purchaser and the manufacturer.

 

Mechanical properties

Standard Steel Grade BK (cold finished/hard) BKW (soft) GBK (annealed) NBK (normalized)
Yield Strength
(Re)		 Tensile Strength
(Rm)		 Elongation
(A)		 Yield Strength Re
min.		 Tensile Strength Rm
min.		 A
min.		 Yield Strength Re
min.		 Tensile Strength Rm
min.		 A
min.		 Yield StrengthRe
min.		 Tensile StrengthRm
min.		 A
min.
BS 6263-4 CFS 3 360 450 6 280 400 9 170 340 26 215 360 24
CFS 3A 360 450 6 280 400 9 170 340 26 215 360 24
CFS 4 415 520 5 315 450 8 200 400 24 235 410 22
CFS 5 480 600 4 385 550 6 – – – 340 490 20
CFS 6 470 590 5 350 540 7 300 440 22 280 460 21
CFS 7 560 700 4 460 650 7            
CFS 8 575 720 4 470 670 6 300 510 20 340 540 18
CFS 9 575 720 4 470 670 6            
CFS 10 575 720 4 470 670 6            
CFS 11 575 720 4   670 6