Page 37 - Handbook of Materials Failure Analysis

30 CHAPTER 2 Failure analysis in chemical industries

operational conditions, improper material selection, human mistakes, and insuffi-
cient knowledge of corrosion threats also account 68-72% of total failures. The
periodic inspections, monitoring and maintenance procedures could definitely
reduce the risks of premature failure of plant, and hence would insure the safety
and reliability of a plant [28–29].

2 HOW TO CONDUCT FAILURE INVESTIGATION

In a broad spectrum, the corrosion failure analysis is defined as investigating the
reasons for impairment of a part or a device by the environmental attack. The attack
may be more intense due to the existence of inherent abnormalities in the microstruc-
ture, irregularities in geometry, processing defects, and any variation in operating
conditions.
The incompatible joining of materials, mismatch in material of mating surfaces,
overloading, improper repair procedures, and faulty design consideration could also
reinforce environmental degradation.
The sequence of failure investigation specially in a chemical processing industry
is not similar in every situation and depends on the conditions. Even the resembling
historical case studies preclude the identification of factors due to the complicated
environmental conditions. The one way of investigation could be adopted as dis-
cussed below but not necessarily be true in every case [31].

2.1 UNDERSTANDING THE PROBLEMS
The term “failure” describes the loss of function, service life, and/or fracture which
may impair the functionality and limit safe operation in a chemical process indus-
try. The initial statement of a client is useful for an analyst to categorize failure and
to investigate failure causes which usually address the nature of problem and could
customarily be related to the analysis previously conducted. It is also imperative to
gather more and more background information of the process, equipment, and/or
system before collecting information and samples from the incidence site. It is also
the responsibility of a client to bring analyst in time and should disclose the reality
and possible reasons of the failure. The cooperation of a client in this regard could
eliminate the risk of misunderstanding and misdirected root cause analysis. It also
shortens the time for investigation by reducing extensive efforts which might be
unwanted. Hiding the reality could seriously divert the attention of an analyst
by missing out the true failure reason and possibly leading to the similar misfortune
in future. After collecting detailed information of the accident, the next step for an
analyst is to scrutinize design information, service history of the system or com-
ponent, reviewing maintenance records, monitoring environmental and process
transient conditions.