Customer: Couronnaise de Raffinage
End-User: Shell Petit Couronne Refinery
Location: Petit Couronne, Rouen, France
Project: Repair of damaged foundation, replacement of all anchor bolts, redesign of crosshead support base, and regrouting of all elements.
Equipment: K-6510 Recycle Gas Compressor
Work Period: 11 July 2005 – 21 July 2005
The compressor in question is a Burton Corblin type 164 ME 250 single cylinder compressor, driven through belts by a 45 kW electric motor at 500 rpm. The machine was installed in 1977, without using any proper grout – i.e. directly on the concrete, and has been operating practically continuously for years.
During this time the lubricating oil leaking out from the crankcase has worked its way into the concrete, and down the separations between anchor bolt and the concrete fill material used as grout, and between this grout and the foundation itself. The concrete under the crankcase has lost its resistance to compression, so the machine has been shimmed with thick steel plates. Since these steel plates were resting on deteriorated concrete, they did not help the situation. The vibrations have been increasing and the anchor bolts have been deformed by the impacts of the crankcase. Finally one of the crankcase anchor bolts sheared completely, and the unit came to an undignified and catastrophic halt. The crankcase and the crosshead casing were both severely cracked, and have since been repaired by metal stitching.
The original brief was to repair the foundation, remove the damaged grout/concrete, and replace the crankcase and crosshead support anchor bolts. However, after removal of the motor mounting slides, the anchor bolts were found to be badly corroded, and these were also cored out and replaced. Since there is the possibility that the crankcase may be replaced by a new or reconditioned unit in future, asoleplate installation was recommended, and designed. There was some confusion about the exact dimensions of the crosshead support, since the existing damaged support did not match up with the original drawings. Eventually a consensus was reached as to the probable correct dimensions, and the client accepted the fact that these were possibly not accurate, and that in-situ machining might be required when the repaired unit is returned.
The crosshead support, the soleplates, and the motor bases were therefore aligned in vertical and horizontal planes, and grouted in place with ALPHATEC® 800 Epoxy Grout. Grade 8.8 fully threaded rod was used as the replacement anchor bolt material, and was fully grouted to a depth of at least 12 diameters. The upper part of each anchor bolt was isolated from the grout to allow for a proper stretch length of at least 6 diameters.
Once the machine has been reinstalled it is important that the bolts should be tightened to the proper loading, which we define as 50% of the yield strength. Grade 8.8 bolt material has a nominal yield strength of 640 N/mm2, so the recommended fastening load is 320 N/mm2. The size, cross-sectional area, fastening load, and torque to apply for the bolts used are as follows:
Crankcase anchor bolts: M27 459 mm2
146,880 N 793 N.m
Crosshead anchor bolts: M22 303 mm2
96,960 N 427 N.m
Motor base anchor bolts: M22 303 mm2
96,960 N 427 N.m
In order to protect the foundation concrete from further oil ingress, the top surface and a short distance down the sides was chipped, and epoxy grout poured overall as a protective capping.