Forensic Evaluation - Evaluation of Damaged Grout at the base of Coker Units.

Forensic Evaluation – Evaluation of Damaged Grout at the base of Coker Units.

Problem:

A proposed repair program at a refinery suspected an epoxy grout as the material used at the base of a series of Coker units; the grouts have been damaged. Specification covering the earlier work performed was not available. Several samples were taken from a number of the drum units. Two damaged grout samples were submitted to our Consultancy to determine the type of grout material and the probable cause of the damage to the grout.

“As received” damaged sample with rounded edges (photo)

Evaluation Method/Process:

Four analytical methods were used to evaluate the two damaged samples:

Petrographic analysis
Scanning electron microscopy, SEM
Thermogravimetric analysis
X-ray diffraction

Efflorescence cover on other irregularly shaped damaged sample, “as received” (photo)

Findings:

Through Thermogravimetric analysis and X-ray diffraction it was concluded that one of the samples was an epoxy grout; the other was a cementitious grout.

One of the significant contributors to the damage was attributed to the aggregates used; it was marginal in quality, with inherent cracks in them.

Petrographic photo shows delaminating epoxy matrix from aggregates (photo)

Petrographic photo shows cementitious binder surrounding a cracked aggregate (photo)

SEM photo showing nondescript epoxy binder and aggregates

SEM photo showing cementitious hydration product.