offshore external corrosion guide

8/2/2019 Offshore External Corrosion Guide

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Corrosion policy

Regulation 5 of the Provision and Use of Work Equipment Regulations 1998 requires that Every employer shall

ensure that work equipment is maintained in good repair. To achieve this requirement, the associated guidance to

the Regulations provides further information on three maintenance management options.

OSDs preferred option is that dutyholders use planned preventive maintenance, thereby precluding deterioration.

However, where a dutyholder allows components to degrade and/or corrode as part of a condition-based option,

performance standards must exist which define the point at which the component needs to be repaired or

replaced. Such performance standards should be quantifiable and capable of being measured effectively and

consistently.

The performance standards need to be supported by sound engineering justification and should be consistent with

the basis of design, taking account of any changes to service conditions. This should include the necessary safety-

related strength and/or serviceability requirements of the component necessary to define the quantitative

performance standard.

Where such components are part of Safety Critical Elements, the components should be verified by an IndependentCompetent Person. Such verification should include both the justification for and ongoing compliance with the

performance standard.

Purpose

This guide is intended to enable OSD inspectors to make consistent judgement on the extent of external

corrosion related to the installations hydrocarbon systems. The guide identifies a sample of six common forms

of external corrosion and provides information on:

I where to look; and

I what to look for.

The six areas of concern are:

I corrosion under insulation (CUI);

I firewater mains and deluge system;

I flanges and plant bolting;

I valves;

I pipe supports and pipe coatings; and

I threaded plugs.

Health and Safety

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Offshore external

corrosion guide

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Corrosion under insulation

Where to look What to look for

General target areas I Water traps, eg low points,

brackets, penetrations,support rings

I Areas of personnel traffic

I Insulation terminations

Cladding condition I Rusty surface/corrosion holes?

I Joint sealant condition?

I External condensation/icing?

Penetrations I Sealed/sealant in good

(eg branches, supports, condition?

structural members) I Signs of water ingress/wet

insulation?

I Salt encrustations around

penetrations?

Joints I Are the joints generally in

good condition?

I Insulation visible through joints?

I Deformed/poor fit?

Damaged insulation I Deformed?

I Signs of being walked on?

I Impact damage?

Corrosion I CUI inspection programme?

management I Personnel protection replaced

by cages?

I CUI problems/failures?

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Firewater mains and deluge systems


General target areas I Mixed metals, non-metallic?

I Spray and monitor nozzles

I Temporary repairs

I Valves

I Flanges

Spray and monitor I Blocked?

nozzles I Salt encrustations?

I Corrosion products?

Temporary repairs I Number?

I Leaking?

I Repair type?

Flanges I Leaks?

I Dissimilar metals?

Valves I Leaks?

I Dissimilar metals?

Non-metallic piping I Leaks?

I Joint condition?

I Local colour changes?

Corrosion management I Is it a wet or dry system?

I What is the inspection programme?

I How often is the deluge system

tested?I What is the corrosion

management programme?

I What is the failure history?


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Bolts and nuts


General target areas I Mixed metals

I

ValvesI Flanges

I Pumps

I Xmas trees

I Corroded bolts/threads

I Fractured bolts

I Nuts grossly enlarged by

corrosion product

Corrosion protection I Unprotected

I Grease

I Denso tape

I Galvanised

I Nickel-plated

I Corrosion-resistant alloy

Corrosion management I What is the inspection

programme?


Valves


General target areas I ESDVs

I Xmas trees

I Choke valves

I Pressure relief valves

I Drain valves

I Block valves

What to look/ask for I Corroded handles/wheels?

I Corroded valve stems?

I Leaking stems?

I Leaking flanges?

I Leaking valve bleed plugs?

I Are valves properly supported?

I Paint condition?

I Corrosion-resistant materials?

Corrosion management I What is the valve test

programme?

I What is the inspection

programme?



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Pipe supports and pipe coatings


General target areas I Piping

I

Pipe supportsI Spring supports

I Fretting surfaces

What to look/ask for I Paint condition?

I Thick corrosion deposits?

I What are the paint and fabric

maintenance programmes?

I What action is taken to ensure

areas around pipe supports are

painted?

Corrosion I What external corrosion

management problems have there been?

Threaded plugs


General target areas I Valve bodies

I Xmas trees

I Piping usually low and high

locations on pipe work

What to look/ask for I Are pipe plugs rare or

numerous?

I Are there dissimilar metal

issues?

I Condition of threads?

I Leaking pipe plugs?

I Rust stains?

Corrosion management I Replacement by non-threaded

equipment

I No dissimilar metals

I Replacement and thread

inspection programme

I What failures have there been?


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Published by the Health and Safety Executive 09/06

Health and Safety

Executive

5 of 5 pages

This booklet is not available from HSE Books. It can be downloaded from the HSE website at:

www.hse.gov.uk/offshore/index.htm

Crown copyrightThis publication may be freely reproduced, except for advertising, endorsement or commercial purposes.

First published 09/06. Please acknowledge the source as HSE.

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