BS6323-4 BK BKW GBK NBK GZF NZF Cold Finished Seamless Steel Tubes Grade CFS1 CFS2 CFS3 CFS4 CFS5 42CrMo4

Standard: BS6323-4    Seamless and Welded steel tubes for automobile,mechanical and general engineering purposes
Part 4: Specific requirements for cold finished seamless steel tubes          

                            
Applications: for Auto industry / for machinery use/mechanical and general engineering purposes           
                                                          
Size range: O.D.:6-280mm     W.T.:1-30mm      L:max12000mm                                        
 

Method of manufacture:

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

It is permissible for cold finished tubes to have on internal and external surfaces an adherent layer of residual to subsequent processing, then their removal shall be the subject of an agreement between the manufacturer and the purchaser.

Delivery Condition:

The tubes are supplied in one of the following condition:

a. Cold finished/hard (cod finished as drawn) : BK

b. Cold finished/soft (lightly cold worked ):  BKW

c. Annealed: GBK

d. Annealed (including de-scaling): GZF

e. Normalized: NBK

f.  Normalized ( including de-scaling): NZF  

Tests:

Flatenning tests

Leak tightness test- Eddy current test

"NOTE  Welding of tubes of grades 3,3A and 5 does not require special techniques but care should be taken and welding carried out in accordance with guidance given in the appropriate British Standard for welding,e.g. BS 5135.The welding of other grades shown may require special techniques.
aGrade 3A shall be suitable for case hardening purposes.   
bGrain refining elements may be added at the option of the manufacturer .   
cIf tubes in the BK and GKW condition are subsequently welded,brazed or heated the mechanical properties in the heat affected zone may be reduced to those given for the delivery condition GBK or NBK.
dSteel within the limits shown,but in accordance with the chemical composition of BS 970-1,may be supplied if agreed ate the time of order or enquiry."