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Journal of Failure Analysis and Prevention

, Volume 13, Issue 5, pp 595–600 | Cite as

Early Failure of High Pressure Screw Pumps: Shaft Fracture

  • Saher Shawki
Technical Article---Peer-Reviewed

Abstract

The repeated failure of high pressure screw pumps operating in a petroleum oil field required serious attention. Two pumps (out of three) suffered catastrophic failure after relatively short times (6 and 9 months) of operation. The failure was manifested, in both cases, by a circular crack in the driven shaft that developed to complete fracture. Comprehensive failure analysis of one of the pumps showed that the shaft cracked due to fatigue as a result of the rotary bending process caused by misalignment. In addition to the faulty operation and inaccurate maintenance, the material of construction, martensitic stainless steel 420, in the as-built condition was considered to be a major cause of damage. Type 420 attains maximum corrosion resistance, increased strength, and hardness when it is fully hardened. However, a stress relief operation should follow the hardening treatment as toughness tends to decrease with increasing hardness to oppose fatigue cracking.

Keywords

Pumps Shafts Martensitic stainless steel Fatigue failure Fatigue cracking Brittle fracture 

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Copyright information

© ASM International 2013

Authors and Affiliations

  1. 1.Central Metallurgical Research & Development Institute (CMRDI)Helwan, CairoEgypt

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