DIN 1629

DIN 1629 include 3 basic steel grades (ST37, ST44, ST52.), this standard specifies the seamless circular Tubes of non alloys steels that are used in construction of chemical plant, pressure vessels, pipe system and general mechanical and engineering purposes.

The subclauses marked with a single dot give specifications which are to be agreed upon at the time of ordering.

The subclauses marked with a two dots give specifications which optional and may be agreed upon at the time of ordering.

• for Atuo usd;
• for machinery use;
• Oil cylinder tube
• Motorcycle shock reducer steel tubes
• Auto shock reducer inner cylinder

1.1 This standard applies to seamless circular tubes and pipes(hereinafter briefly referred to as “tubes”) made of unalloyed steels as listed in table 1. These tubes are predominantly used in the constructin of chemical plant, vessels, pipework and for general mechanical engineering purposes. They are designed to meet high performance requirements. Normally there are no limiting vaiues or the maximum permissible working pressure of these tubes. The permissi l working temperature shall not exceed 300℃ are specified in Appendix A.)

The limits of application and other specifications given in this standard shall apply except in cases here other specifications are contained in codes of practice for specific fields of application, e.g. the Technische Regeln fur Dampfkessel (TRD) (Technical rules on steam boilers) or the Technische Regeln fur Druckbehalter (TRB)

(Technical rules on pressure vessels), AD-Merkblatter (AD Instrucation sheets).

Chemical composition of steels for seamless circular tuves subject to special repuirements

Chemical composition of steels for seamless circular tuves subject to special repuirements

Steel grade		Type of deoxidization (R, killed (including semi-killed)) (RR, fully killed)	chemical composition, % by mass
Symbol	Material number		C	P	S	N¹)	Addition  of nitrogen fixing elements (e.g.not less than  0,020% Aitotal
St37.0	1.0254	R	0.17	0.04	0.04	0.009²)	-
St44.0	1.0255	R	0.21	0.04	0.04	0.009²)	-
St52.0³)	1.0421	RR	0.22	0.04	0.035	-	Yes

1) A content in excess of the maximum value started is permitted if a phosphorus content less than the maximum specifled by 0,005% P per 0,001% N is observed. However, the nitrogen content shall not exceed a value of 0.012% in the cast analysis and 0,014% in the product analysis.

2) The specified maximum values do not apply if the steels are supplied with the RR (instead of R) type of deoxidization

3) The content shall not exceed 0.55% Si and 1,06% Mn in the cast analysis or 0,60% Si and 1,70% Mn in the product analysis

table 3. Amounts by which the chemical composition in the product analysis may deviate from the limiting values applicable to the cast analysis {see table2}

Table 3

Element	Amount by which the product analysis may deviate from the limiting values applicable to the analysis % by mass
C	+0,02
P	+0,010
S	+0,010
N	+0,001¹)

Amounts by which the chemical composition in the product analysis may deviate from the limiting values applicable to the cast analysis {see table2}
¹) A contant in excess of the maximum value stated is permitted if a phosphorus content less than the maximum specified by 0,005% P per 0,001% N is observed. However, the nitrogen contant shall not exceed a value of 0,012% in the cast analysis and 0,014% in the product analysis (this does not apply to the RR type of deoxidization.

Table 4

Mechanical properties of tubes in the as delivered condition at room ternperature For wall thickness exceeding 65 mm, the values shall be agreed at the time of ordering

Steel grade		Upper yield stress ReH for wall thicknesses, in mm,			Tensile strangth Rm	Elongation after fracture A5
Symbol	Material  number	up to 16	over 16 up to 40	over 40 up to 65	N/mm²	lonigtudinal	transverse
St 37.0	1.0254	235	225	216	350²) to 480	25	23
St 44.0	1.0256	275¹)	265¹)	255¹)	420²) to 550	21	19
St 52.0	1.0421	355	345	335	500²) to 650	21	19

Chemical composition (%) of DIN1629

Grade	C max	Si max	Mn	P max	S max
DIN1629 St 35	0.17	0.35	≥0.40	0.025	0.025
DIN1629 St 45	0.21	0.35	≥0.40	0.025	0.025
DIN1629 St 52	0.22	0.55	≤1.60	0.025	0.025

Mechanical Properties of DIN1629

Grade	Yield Strength (Mpa)	Tensile Strength (Mpa)	Elongation (%)L	Elongation (%)T
ST37.0	≥235	350-480	25	23
ST44.0	≥275	420-550	21	19
ST52.0	≥355	500-650	21	19