Oil & Gas Management

Refinery Corrosion Control

Introduction

OGM/Lloyd's Register Capstone has provided Corrosion Studies for all types of refinery operating units as well as many chemical and petrochemical plants. The studies have often been used to support a risk based inspection program or implementation of Reliability Based Mechanical Integrity program.

Key Benefits

Experienced corrosion engineers to identify likely damage mechanisms for each piece of equipment
Appropriate inspection methods recommended for the identified mechanisms
Well-documented corrosion study for future reference
Improved understanding of damage types and locations for plant inspection and engineering

Details

The study starts with a clear understanding of the process and then digs into the details of each equipment item to accurately determine which affects the process has on the probability and consequence of a failure.

The design and operating conditions for each equipment item are reviewed along with associated inspection and maintenance history to identify potential failure mechanisms and damage rates. Capstone's corrosion engineers have extensive experience with all of the known failure mechanisms within the refinery environment including:

Internal corrosion from ammonium bisulfide, naphthenic acid, wet H2S, carbonic acid, various types of chlorides, HF acid, sulfuric acid, sulfurous acid, and caustic
External corrosion from high temperature oxidation, atmospheric conditions, and corrosion under insulation
Cracking mechanisms such as amine stress corrosion cracking, stress-oriented hydrogen induced cracking, wet H2S cracking, carbonate stress corrosion cracking, chloride stress corrosion cracking, and polythionic acid stress corrosion cracking
Material degradation mechanisms such as creep and high temperature hydrogen attack

The potential for upset conditions is also evaluated. These upset conditions may initiate unexpected failure mechanisms as well as compromise equipment design, as in the case of brittle fracture. Capstone provides experienced personnel who understand the process, know how to interpret the equipment data, and ask key questions to uncover unexpected situations. The corrosion study can be documented by marking corrosion loops on existing Process Flow Diagrams (PFD'S) or by creating Corrosion and Materials Drawings.

Corrosion Control Documents are developed for each unit based on the requirements of the project. The Corrosion Control Documents can include:

Process overview
Critical process variables
Summary of damage mechanisms anticipated in the unit
Detailed analysis of each equipment item and piping corrosion loop in the unit
Materials of construction
Expected or confirmed damage mechanisms
Potential fouling
Methods to control deterioration
Inspection and monitoring recommendations