F. Fantechi et M. Innocenti, Chloride stress corrosion cracking of precipitation hardening SS impellersin centrifugal compressor. Laboratory investigations and corrective actions, ENG FAIL AN, 8(5), 2001, pp. 477-492
17-4 PH, precipitation hardening stainless steel (ASTM A 705 Grade 630), is
widely employed in several industrial fields because of its favourable com
bination of excellent mechanical properties and good corrosion resistance.
An important application of 17-4 PPI is the construction of centrifugal com
pressor impellers, where performance benefits from the steel's high mechani
cal resistance even when it is necessary to limit hardness, for example, as
per NACE MR0175, to avoid devastating sulphide stress cracking phenomena i
n sour environments. Nevertheless, there has been a case in which impellers
made of 17-4 PH have been subject to failures. It was a centrifugal compre
ssor employed in a gas lifting service in which the fluid entrained water w
ith a high level of salinity. Laboratory failure analysis attributed the da
mage to chloride stress corrosion cracking phenomena and was followed by a
study on the behaviour of 17-4 PH in chloride-rich environments and on the
action to take to avoid damage causing forced outages and loss of productio
n. (C) 2001 Elsevier Science Ltd. All rights reserved.