Alphatec – Grouting Specialists Figure 5: Grout Replacement
These jacks were placed on epoxy grout pads to ensure proper stress distribution into the concrete. Corrosion of the baseplate was found to be negligible. The remaining grout was then chipped out.
The bearing pedestal grout was then chipped out, and the sleeves around the anchor bolts cut away.
Note the steel packers driven into the sleeves to push the anchor bolts into the correct position. This became something of a pattern, since all anchor bolts on this machine appear to have been ‘persuaded’ into their final positions. Work on the crankcase and frame extensions eventually started on 21 June, and progressed rapidly.
Approximately 200 mm of grout and oil-soaked concrete was removed under the crankcase and frame extensions, as can be seen in the picture below.
Grout removal around the pipe supports resulted in the complete demolition of the plinth in some cases, since there was no bond at all to the floor level concrete.
Alignment
After the grout had been completely removed, the crankcase was aligned. This work was carried out together with the mechanical contractor, Thyssen Krupp Xervon, and a reasonably good alignment was achieved, considering the age of the machine.
Crankcase and frame extension grout was poured after alignment. The bearing pedestal was next aligned to the compressor and grouted and finally the motor was adjusted using the ALPHAPAD and OPTALIGN systems to realise a good driveshaft alignment.
16
Grout Replacement
Formwork was prepared and set in place to contain the grout pour. ALPHATEC 800 epoxy grout was mixed and poured to properly encapsulate the machine bases. Forms were removed the following day and anchor bolts finally tightened after transferring the load from ALPHAPAD to grout by cutting off the protruding steel tubes.
Additional epoxy grout was poured in the areas between the machine base supports to provide an oil-impervious surface.
Anchor bolts were tightened according to the following schedule: •
M42 bolts (motor baseplates) 1,600 Nm;
• • •
M30 bolts (crankcase and frame extensions) 630 Nm; M24 bolts (crosshead supports, etc) 320 Nm; and M18 bolts (bearing pedestal, etc) 130 Nm.
These figures are based on the assumption that the bolt material has a
tensile yield strength of 300 N/mm2, and that the bolt tension should be approximately 50 % of this figure. The motor bolts should be tightened to 1,740 Nm according to this calculation, but 1,600 Nm was the maximum achievable with the equipment to hand and is considered to be satisfactory. n
On behalf of:
ALPHATEC ENGINEERING (EUROPE) ARONUI TECNOLOGIAS S L Giles Goldsbro
HYDROCARBON WORLD – VOLUME 6 ISSUE 2
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