Valve cages are the surrounding part of the plug which is situated inside the body of the valve. The vlave is fitted to regulate the flow in a pipeline, and the valve cage is one of the greatest factors to determine the flow in the valve. With the movement of the plug, there is a lot more space for the flow and when the plug is moved in, it closes the opening. The openings are also an important part because the design and the layout have a big impact on the material flow passing through the pipeline. Cages are also used to guide the plug to the seat of the valve for a good shutoff, substituting the guiding from the bonnet.
There are also valve cages of different types like exhaust valve cages and control valve cages. These valve cages need to be repaired and replaced in their lifetime. For crankshaft repairs, there are various companies which offer full reconditioning services to exhaust valve cages. In the cleaning process, all the cages are stripped down and should be cleaned with latest chemical cleaning machines. All parts should be inspected and calibrations should be taken and recorded wherever necessary. In the crankshaft repair work, the cages are hydraulically pressure tested to assure a satisfactory repair. The valve cage repairs can be done for many types of engines like Mirrlees and Wartsila and many more.
It should be kept in mind that the valve cages should have new valve seats Electron Beam welded to the OEM standard. The welding should not be the cheap T.I.G welding process, as it can lead to catastrophic failure and lack of fusion because of water leakage. One should also be aware that valve cages can be availed in many materials like brass, alloy steel, brass, carbon steel, stainless steel, monel, 440C stainless steel and stellite valve ball guides can also be availed in case of severe service.
The exhaust valve cages can be reconditioned in ways like - the damaged seats of the cages can be machined back to sound base material, built up and re-profiled the seating area can be re-stellited and re-machined back to original dimensions. The blocked internal cooling passages can be repaired by replacing the nose with steel forging welded into the place. In reconditioning, it should be taken care of that the welding parameters are correct and that the pre-and post -heat treatment takes place for removing the likelihood of cracking through the use of incorrect materials and procedures. Every care should be taken for good maintenance.