Tribological analysis and anti-galling design of ocean-floor pile reformation tool

• Published in: Wear 1995-03, Vol.181-183 (II), p.889-896
• Main Authors: Shaffer, S J, Glaeser, W A, Ostgaard, J T
• Format: Article
• Language: English
• ISSN: 0043-1648
• DOI: 10.1016/0043-1648(94)07095-4

A tribological analysis was performed on the sliding interfaces and lubrication system for a high capacity, underwater pile reformation tool. The 56 000 kg tool has a maximum wedging load of 5.0x10 exp 4 kN and must operate at a water depth of 100-250 m. No previous application or data could be found for similar high contact stresses and low sliding speeds, although sliding bridge bearing pads and airframe bearings gave some direction. The 5 deg C salt water environment, however, imposed the additional factor of corrosion, and it complicated grease selection since both water resistance and pumpability were competing requirements. Based on the analysis, material selection and design modifications were proposed. Using a high-capacity, flat-on-flat friction test rig, laboratory tests were performed to obtain both sliding friction and wear data at contact stresses up to 690 MPa. The results were used to validate the effectivenss of the recommendations and to compute wear coefficients from which service lifetime was predicted. Aluminum bronze plates were retrofit to the cast stainless steel segments; a baked, porous phosphate and PTFE coating was applied to the carbon steel wedge; grease channel geometry was modified; and heavy duty, MoS sub 2 fortified grease was used.