Steel for tubes and pipelines

According to standard EN 10020, steel is defined as a material, where the weight percentage of iron is higher than that of any other element, and carbon content (C) is less than 2%, which is the usual boundary between steel and cast iron.

Marking system for steel pipes according to EN

EN 10027 – 1	system of reduced marking, the basic symbols.
EN ECISS IC10	additional symbols.
EN 10027 – 2	system of numerical marking.

According to EN 10027-1 standard steel markings are divided into two main groups:

Group 1 - steels marked by the use and its mechanical properties

S	steels for constructions for general use
P	steels for pressure purposes
L	steels for pipelines
E	steels for machine parts (the number indicates the minimum yield strength in N/mm2)
B	steels for concrete reinforcement
Y	steels for stress reinforcement in concrete
R	steels for rails
H	flat cold-rolled products
D	flat products of mild steel for cold forming
T	sheets and strips
M	sheets and strips for electrical engineering

S – steels for construction for general use

(e.g. S235JRH, S355J2H, S420NLH)
- 235 – minimum yield strength in N/mm2

for general use
J – value of impact strength (27J)
R – ambient temperature, 0 – temperature 0°C, 2 – temperature -20°C
H – hollow profile (Hollow Section)

for fine grain steels – basic series
N – normalized structure
H – hollow profile
for fine grain steels – low temperature series
N – normalized structure
L – low temperature series (Low)
H – hollow profile

P - Steel for pressure purpose

(e.g. P235TR1, P265GH)
235 - minimum yield strength in N/mm2

T - steel for tubes (T - tube)
R - ambient temperature (R - room temperature)
H - high temperature
L - low Temperature
N - normalized or formed
1, 2 - quality group
TR1 – steels for tubes for transporting media
TR2 – steels for tubes for pressure equipment and pipelines (PED, AD 2000 Merkblatt)
G - general characteristics, notice for the second character

L - steels for pipeline tubes

(e.g. L210GA, L245NB)
210 - minimum yield strength in N/mm2

G - General, general characteristics, a letter for notice of the following significance in the second character
A - grade requirements for pipeline tubes
N - steel normalized or formed
Q – heat treated steel
M - steel, thermomechanically rolled
B - grade requirements for pipeline tubes(napr. L210GA, L245NB)

E – steels for machine parts

Steels for tubes for machining - E355 + AR, E 355 + N:
- 355 – minimum yield strength

+ AR – no heat treatment is required
+ N – normalized (annealed) or rolled

Steel marked according to chemical composition, for example. 20MnV6
- guaranteed mean content of C 0.20%, guaranteed content of Mn and V
+ AR – no heat treatment is required
+ N – normalized (annealed) or rolled

Steels for machining without subsequent heat treatment
unalloyed steel E235, E275, E315, E355, state +AR or + N

Steels with specified impact strength properties (fine grain) E275K2, E355K2
- K2 - guaranteed value of impact strength 40J (K) at -20 ° C temperature

Steels for thermal and chemical-heat treatment of parts after machining
- steels type C22E (C - steel with carbon content 0.22%, E - indicates the maximum controlled content of S and P)
- steel 38Mn6 (guaranteed medium content of C and guaranteed content of Mn)

Group 2 - steels marked according to chemical composition (4 subgroups)

Non-alloy steel

(with the exception of free-cutting steel)
letter C and the number corresponding to 100 times the mean range value specified for the content of carbon (C22)

Non-alloy steel

containing Mn> 1% and alloy steels content of individual alloying elements below 5%
a) number corresponding to 100 times the carbon content
b) chemical symbols of alloying elements in order of decreasing content of elements
c) numbers are set up by the alloying elements content (25CrMo4)

Alloy steels containing min. of one element over 5%

a) characteristic letter X (X11CrMo9-1)
b) number - 100-times the mean of carbon content
c) the chemical symbols of alloying elements
d) numbers which are set up according to the alloying elements content

High speed cutting steel – marking

a) characteristic letters HS (HS 6-5-2)
b) numbers which are set up by the alloying elements content

The EN ECISS IC10 Standard provides additional symbols for steels (Groups 1 and 2). These symbols are placed at the end of the mark of the steel (S 275 J0).
In addition, symbols are added to steel products. These are separated from the previous symbols by a plus sign (S 275 J0+A).

Symbols for steel tubes
G - other characteristics (depending upon the need 1 or 2 digits)
H - hollow profile if necessary steel for higher temperatures according to the type of steel (S, P)
L - steel for low temperature
R - steel for standard temperature (ambient temperature)
M - thermomechanically rolled
N - normalized or normalized rolled
Q – heat treated
T - steel for tubes

EN 10027-2 contains the system of numerical marking.
The first number is 1 - steel, followed by two digits steel group and of the serial number of steel.

Carbon equivalent
Based on the agreement maximum value of carbon equivalent (CEV) as a measure of the weldability of steel according to the formula may be set up:
CEQ = C + Mn /6 + (Cr + Mo + V)/5 + (Ni + Cu)/15