- Steel grades: by rule, GSM tubes are produced in St 34 – St 37 – St 42 – St 52 or equivalent grades.
- Tubes with wall thickness higher than 8 mm are produced in St 34 – St 37 – St 42 steel grades or equivalent.
- GSM tubes are supplied with internal fin removed, deburred square cut plain ends
- Lenghts: tubes are usually produced in random length of about 6 meters.
The 3% of supplied tubes may be shorter than 6 m, down to a minimum of 4 m.
When required, tubes may be produced in fixed length between a minimum of 5 and maximum of 12 meters.
- on outside diameter: + 0,5%, in any case not less than + 0,25 mm
- on thickness: + 10%
- on fixed lenght: – 0 + 50 mm
- on weight: + 10%; – 8% for each tubes; + 7,5% for lots of 10 ton at least.
- Tests: tubes are submitted to tensile, flattening and expanding tests. Their soundness is guaranteed by non-destructive tests by means of eddy current instruments. If required, tubes can be tested by diverted magnetic flux instruments.
- Certificates: for each supply a certificate attesting conformity with the order.