Howden Thomassen Compressor Regrout and Resin Injection

The Problem and Solution

The foundation block of the Thomassen compressor C.20-4 type, which was installed in the early seventies, had several horizontal plans of potential cold joints with oil penetration and flow out, resulting in anchor bolt looseness and lack of effective clamping.

Alphatec Engineering conducted resin injection repair of the foundation using Alphatec® 342 resins and grouted the foundation with Alphatec® 800 epoxy grout. They also installed anchor bolts onto steel sleeves and added a stack of square shim plates under the levelling screw to ensure proper support for the compressor. The team thoroughly cleaned all surfaces to be in contact with the epoxy grout to prevent further damage.

The Procedure

Alphatec Engineering was tasked with the rehabilitation of the foundation of a Thomassen compressor C.20-4 type driven by a 950 kW SMIT electric motor. The Bayern Oil technical and mechanical team prepared the compressor, installed dust and heat protective sheets and dismantled the motor (for revision) and removed all piping and wiring around the compressor which impeded access, or which might be subject to damage during the repair works. 

After the first step involved drilling 16 holes of 65 mm in the foundation to serve for later pressure Alphatec® 342 resin injection repair. The depths of the drilled holes ranged from 2.5 to 4.0 metres, which were sufficient to penetrate all significant cold joints and access the underground mat. Chipping out the grout and damaged concrete was then done diagonally from opposite sides of the compressor plinth while supporting the crankcase and frame extension bases with the ALPHAPAD® system and under the cylinder head support.

Next, square shim plates were stacked instead of a round metal pad under the levelling screw, which reduced the effectiveness of the anchor bolts clamping force. This means that the compressor was really supported by jacking screws. Anchor bolts were installed onto steel sleeves, which were also filled with cement grout. The original anchor bolt installation had no provision for material stretching, thus the anchoring system was very ineffective.

Under the motor soleplates, the grout was removed and a proactive cap of 50-60 mm of Alphatec® 800 epoxy grout was mixed and poured. The team then used a pneumatic plunger pump to inject Alphatec® 342 resin into the 16 injection holes at pressures up to 300 bar but usually lower, to repair the foundation.

Before grouting, all surfaces in contact with the epoxy grout Alphatec® 800 were thoroughly cleaned, including grinding and wire brushing of corrosion and old grout, dusting, wiping, and solvent cleaning of rests under the crankcase oil pan. After emptying the grout part of the metal sleeves, PE foam and duct tape was wrapped around the exposed part of the anchor bolts to ensure that there is a good stretch length and stress-free anchoring.

Conclusion

Alphatec Engineering successfully addressed the foundation issues of the Thomassen compressor C.20-4 type at Bayern Oil, using innovative techniques and high-quality products. This project is a testament to our expertise in restoring damaged machinery foundations to their original condition while ensuring their reliable and efficient operation.

Our advanced epoxy resin-based grouts, reinforced with inert fillers, provide exceptional stiffness and heat resistance, making them an ideal solution for repairing damaged foundations or installing new machinery in compliance with OEM and API RP 686 standards.