Berth 2 crane: Hook hoist & jib hoist hub repairs

Mid 2013 – May 2014

(1) On 31/5/2013 during the annual inspection of the Schat Harding crane on berth 2, it was found that the hubs supporting the luffing and jib hoist cable drums were in poor condition due to corrosion.

(2) Alliance lifting gave certification that the crane was fit for another year of service, stating that although the corrosion was not at a stage where it would cause a lack of structural integrity, it should be addressed before the next inspection a year from the date of the current certification.

(3) Sem maintenance attempted to remove the cable drums in question in order for blasting/painting and any resulting over-plating to be carried out.

(4) The cable drums were seized to the shaft and even with a jacking setup mounted onto the assembly, it was not possible to remove them:

(5) It was decided that because such force would be needed to remove the drums, that new ones should be sourced before removal was attempted again in case damage occurred.

(6) Schat Harding were contacted and a site visit arranged to assess the problem.

(7) The below report was given following the site visit by Schat Harding 0n 29/7/2013:

The following order was raised covering new luffing and hoisting cable drums, shafts, bearings and oils seals:

The replacement parts arrived at Sem on 28/11/2013:

High winds and poor weather were likely to affect the progress of the job should it be attempted over the winter, so the work was postponed until the summer months.

Week commencing 12/5/14 the work was revisited:

The jacking assembly used previously was set up and once the cables had been unwound from the drums they were removed relatively easily.

Hook hoist hub following removal of drum:

As identified by Alliance lifting, the cable drum hubs were indeed in poor condition with badly corroded reinforcing gussets:

Closer view of corroded gussets:

Also, the main body of the hook hoist hub was thinned due to corrosion:

Initially, only installation of replacement gussets was anticipated, but due to the poor condition of the hub in general, the decision was taken to install a reinforcing sleeve:

The sleeve was installed and new gussets welded in place:

Hook hoist hub repairs painted to Sem specification:

Bearing cover plate removed and bearing greased:

New bearing cover was fitted following greasing.

Jib hoist hub following removal of drum:

Corroded gusset:

The jib hoist hub was in much better condition than the hook hoist hub, with only one corroded gusset, which was replaced:

Jib hoist hub repairs painted to Sem specification:

There was an area of the gearbox below the jib hoist hub that was corroded as per below picture:

Once grit blasted, there was found to be maximum of 8mm loss in the area. When the amount of loss was compared to a nominal thickness of 28mm for un-corroded areas, it was not deemed a cause for concern.

The area was painted to Sem specification to arrest further corrosion:

Replacement bearing covers were fabricated and fitted as originals were corroded:

Additionally, two of the reinforcing gussets on the casing of the jib hoist gearbox were also replaced due to corrosion:

And painted to Sem specification:

Prior to painting, an MPI inspection was carried out on all of the welds on the reinforcing steelwork installed, as per following report:

It was noted that the internal surfaces of the existing cable drums were badly corroded as per below photographs.

Hook hoist cable drum:

Jib hoist cable drum:

To prevent the corrosion getting to this point again, the drums are now to be prompted by the CMMS system in use at Sem to be removed every 5 years and their condition assessed, in line with the replacement of the hook & jib hoist cables.

Replacement hook hoist cable drum:

Replacement jib hoist cable drum:

Following the above repairs a further site visit was arranged with Schat Harding to oversee the fitment of the replacement drums, as per following photographs:

Hook hoist drum installed:

Followed by jib hoist drum:

Cables were carefully coiled onto drum using air motor, ensuring that they sat into the scrolled area as designed:

Once jib and hook hoist cables were wound back onto the drums, the crane was put back into its working position and function/load tested, see Appendix 1:

Whilst on load, the air gap between the underside of the main crane pillar and the top of the slewing assembly was measured at 6mm, meaning there has been no change from the date of its installation in October 2011:

The following report was provided by the manufacturer following the hub repairs and fitment of the replacement cable drums:

The following certification was given by Alliance Lifting following the load test:

Appendix 1:

All work has been carried out as detailed within this report:

Joe Edwards – 20140604 -