What is BS 6323-4 standard specification?

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.

Chemical Component

Steel Grae	C	Si	Mn	Cr
CFS 3	0.20 max	0.35 max	0.90 max	–
CFS 3A	0.20 max	0.10 to 0.35	0.60 to 1.00	–
CFS 4	0.25 max	0.35 max	1.20 max	–
CFS 5 b	0.23 max	0.50 max	1.50 max	–
CFS 6	0.30 to 0.40	0.35 max	0.50 to 0.90	–
CFS 7	0.20 to 0.30	0.35 max	1.20 to 1.50	–
CFS 8 c	0.40 to 0.55	0.35 max	0.50 to 0.90	–
CFS 9	0.29 max	0.35 max	1.50 max	–
CFS 10	0.26 max	0.35 max	0.80 max	0.80 to 1.20
CFS 11	0.45 max	0.35 max	1.00 max	0.80 to 1.20

Mechanical Property

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