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Maintenance Welding for Safety-Preparations and Procedures

IP.com Disclosure Number: IPCOM000219894D
Publication Date: 2012-Jul-17

Publishing Venue

The IP.com Prior Art Database

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Page 01 of 29

MAINTENANCE WELDING FOR SAFETY PREPARATIONS AND PROCEDURES


R. L. Hardin and T. A. Quinn

ABSTRACT

     Maintenance welding, at best, is a difficult, time consuming process. Materials are no longer new, properties of these materials may differ from the original state due to service life and service conditions, welding materials used for the original weld may no longer be available, and Code requirements may have changed. To maximize the chances for obtaining successful maintenance welds
and to have these welds perform safely in service, preparations before welding and correct implementation of these preparations
are all important. These preparations, along with their correct implementation, are presented in a step by step sequence and apply generally to all maintenance welding. In addition, specific areas of troublesome maintenance welding in an~onia plants are discussed and methods for correct repair are presented.


Page 02 of 29

MAINTENANCE WELDING FOR SAFETY PREPARATIONS AND PROCEDURES

Ro L. Hardin and T. A. Quinn

    Maintenance welding, whether for an emergency shutdown or part of a scheduled maintenance program,can be difficult and time consuming, especially when down-time is so often a critical factor.

However, to obtain successful maintenance welds and to have these welds perform safely in service, precautions before welding and correct implementation of the prepared procedures are all important.

    W~ile the purpose of this presentation is to list some of the preparations that will lead to safer, maintenance free welds, th__e decision to plan and prepare is the first and most important step.

Without this decision, planning never begins, the project is hurried to completion, and many necessary items are forgotten or not considered.

     Preparations for welding are those items planned ~rior to,
not after, conmlencement of welding. Implementation of the prepa- ration encompasses the correct "carrying-out" of the planning. Many welds have failed as a result of poor planning or incorrect implementation of the planned procedures. Preparations for maintenance welding include safety, code and insurance items, material condition and identification, written welding and NDE procedures, welder qualifications, metallurgical considerations, nondestructive examination and records.

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Page 03 of 29

Page 2


I. PLANNING

SAFETY

     Is the part safe to weld? Maintenance welding will usually be performed on materials that have been in service or in areas that are in operation. A thorough check of the equipment or piece to be welded must be made to insure that equipment is out of service. Also, any flammable residue remaining in the equipment that could cause fires, explosions, or even harmful metallurgical effects on the weld must be removed. For example, compressed air systems, even though depressured, require a thorough cleaning to insure that no lubricating oil or carbon is present. Areas where welding is to be performed must be thoroughly examined and...