Laying head pipe
Sandvik SAF 2507 LHP for laying head pipe is a high alloy super-duplex stainless steel.
Main characteristics of Sandvik SAF 2507 LHP
- Very high mechanical strength
- Excellent wear resistance at high temperatures
Sandvik SAF 2507 LHP has a coefficient of thermal expansion close to that of carbon steel. This gives Sandvik SAF 2507 LHP definite design advantages over austenitic stainless steels in equipment comprising both carbon steel and stainless steel. The values given below are average values in the temperature ranges.
Metric units x10-6/°C
|Sandvik SAF 2507 LHP||13.5||14.0||14.0||14.5|
Figure 1. Thermal expansion comparison between grades.
- Rolling rods of OD 5,5 mm at speeds up to 150 m/s (this requires LHP with ID ≈ 20 mm)
- LHP with reduced bore sized (ID ≈ 20 mm) should be used for small diameter products (OD = 4 ÷ 12 mm) for a more consistent pattern
Historic development of 5.5 mm wire rod rolling speed, mill capability (m/s)
Figure 2. Forced productivity, sub-optimization.
- Higher rolling speeds → acceleration of pipe wear
- LHP wear → unstable laying ring pattern
- Possibility of wire breaking in pipe ("cobble")
- Wire rod produced with inconsistent mechanical properties and tolerances