Hello Sangeeta

You actual may have a very serious problem here. Depending on how large your cavities are, you may be putting additional dozens of tons of mass onto your wheels. The effect on structure is one things, but your wheels will start having problems as well and these may become very costly.

You will find it difficult to completely seal off the joints. Water may also ingress through imperfections in welds. The only way you can assure this is by very carefully testing all welds and sealing your joints in some fashion, then to pressurize your cavities and monitoring the pressure. That may well be a hassle for you.

Alternately, you can openly drain your cavities in appropriate locations, treat the internal surfaces and then monitor the internal condition regularly.

All the best ■

Any worthwhile specification for a quality shoreline box beam structure will have requested manway access to monitor & repair internal corrosion. You are now obliged to provide such access in a suitable location along with the additional reinforcement.

Who checked your drawings? Are there any breather holes shown: there might be for such a big volume in the tropics.

As Helmut Mayer says there will be a serious problem. Some years back the BSH magazine carried an article describing collapse of a BW boom due to internal corrosion.

If the box girder has internal diaphragms these will have to be pierced, reinforced & treated during the coating procedure. ■

Hello Mr Umarye

The cavity size is significant. Whatever advice comes your way in this forum, it is all subject to the particular conditions of your machines.

In any case, more than likely, you are going to have to create those access means, then

- get someone who is well familiar with the behaviour of machines to thoroughly inspect those internals,

- possibly paint the internal surfaces with paint that should be selected for the particular application,

- possibly add vapour inhibiting powder, and

- regularly inspect those cavities and re-inject the powder if you end up using that.

The faster you act on this, the more money you'll save, and do get expert advice. ■

Dear Mr Sangeeta Angle ,

Whatever drains you want to make and where, be very careful that you do not create stress risers in high tension zones in the structure.

And if you do, take the appropriate measures to prevent a fatigue rupture.

Have a structural stress analysis engineer examine your steel structure and check the recommendations carefully.

Fatigue- and corrosion problems in dynamic constructions are often encountered and is by no means to be neglected as safety and much money can be involved.

TAKE CARE

teus ■

I take it Lloyds, DNV, ABS etc are not involved with your port crane operations.

Hacking holes in the bottom of a crane beam to drain water out is rather rough. You would have to ensure that any hole was big enough to pass water without getting bogged up by scale sediment.

After 3 times of telling. please recognise the size of your problem & take steps to do the job properly. Forum members are, in many cases, professionally obliged to tell you once & only once. You cannot expect commitment from forum members for either of your options. Our comment could then be referred to in any court case which might very well ensue. ■