Lay-up

Lay-up is an industrial process term that refers to implentation of a deliberately created component/system segment/system condition that promotes excellent corrosion control during plant outages of varying durations.  Corrosion control is accomplished by modification of the internal component/system environment during the lay-up period.

One should give due consideration to selection of the specific lay-up method to be used, the means by which lay-up will be implemented, and also to prioritization of the various lay-up activities that must be performed.  All of these factors can have a profound impact on the degree of corrosion protection that will be achieved.

One should also note that the use of improper lay-up procedures may not only fail to provide adequate corrosion protection; but it may also significantly increase the corrosion rate and promote the occurrence of new, and more rapid, forms of corrosive attack.

Localized corrosion, e.g. pitting, MIC, crevice corrosion, dealloying, etc. are all rapid forms of corrosion; and their occurrence is typically promoted by stagnant conditions, i.e. conditions that often exist during lay-up.  These factors must be considered when selecting a lay-up method.

One must also consider the impact of lay-up on multi-metal component/systems.  There is a tendency to select lay-up methods that are suitable for carbon steel.   However, there are circumstances in which a lay-up method compromise should be effected.  For example, lay-up methods that are designed to protect carbon steel may actually promote accelerated corrosion of brass parts.  Determinations of this nature should be made by a corrosion engineer.

Corrosion Resolutions reviews and comments on component/system (wet, dry, or gaseous) lay-up procedures or custom creates such procedures for clients. This work product is produced after thorough review of the mix of materials, their present-day cleanliness state, the environment(s) to which the component/system will be exposed, the anticipated lay-up duration and its frequency, and whether or not the component/system must be immediately available for return to service at any given time.

For more information send email to:  CorrRes@aol.com