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SERVICE TIP

Molds or forms used for manufacturing wet cast pipe require a certain amount of maintenance for production of a quality product. The molds manufactured by Besser - Boone manufacturing location are made with jigs and the bases and tops are gauged to meet close tolerances. Therefore, the handling, use and storage of molds will affect the quality of the product turned out.

Molds should be cleaned and oiled (with a release agent) before each day’s use. This cleaning and oiling operation should be done shortly after the molds are stripped, but in an area away from cages to be used in the next pour.

When the molds are stripped from the finished pipe, they should be moved to an area for cleaning and oiling. The inside and outside form gates should be checked for concrete build-up. One of the easier ways to clean a gate is to make a tool of flat steel with a chisel-type end on it. This is used to run up or down the gate to clean out concrete.

Examining concrete build-up in a wet cast form. 
Contact surfaces must be cleaned and oiled daily for proper performance.

The next step is to clean any heavy build-up of concrete from any surface on the mold. Upon completion of the cleaning operation, the oiling of the mold should begin. Always oil the inside of the outside mold and the outside of the inside mold. It is also practical to occasionally oil the outside of the outside mold, as this will make cleaning easier. The mold should now be in condition to use again.

Bases should be cleaned and oiled before each pour. Here a heavy-duty putty knife can be used to scrape the concrete from the surfaces used. It is very important to clean the flange on which the form sets so the form will be steady and also so the wall thickness will not be affected. After cleaning the base, the base gasket should be checked to be certain that it is not cut or chewed up so that the proper seal can be achieved. Replace it if it is not going to properly seal the form against the base. After this is done, oil the base. Do not over oil and leave a puddle on the bottom surface, as this will affect the appearance and/or concrete in the face of the bell.

A well-cleaned and oiled pallet. Note the clean gasket.

Top rings, tamping tops, tamping platforms (or any other name by which they are called) should also be cleaned and oiled before they are used. All of the machined surfaces on these rings can be cleaned with a large, heavy-duty putty knife to remove all excess concrete. If making Concrete and Round Rubber (C.R.R.) pipe, the snap ring should be carefully removed from the header and cleaned and oiled. It is very important to handle this snap ring with care as it can go out of plane very easily. It is also important to scrape clean the back of this ring, as well as the surface it will be placed against in the top ring. These latter two surfaces should also be oiled. An ice chopper can be used to remove the concrete from the platform surface of this top ring. When oiling this surface, a light dusting of sand should be put over the oil, as this becomes a working surface for the pouring crew and it will make it less slippery.

In replacing the snap ring in the top, be sure to use a wooden wedge against the snap ring to tap it in place. Never use steel against steel. Special attention to the care of the snap ring will mean good joints, and the producer will not have a lot of pipe with "O" Ring grooves used for mortar joint or seconds.

Recommended method of installing a snap ring into a header.

Proper maintenance of wet cast forms means 
longer life for the equipment and a better product.

DO’S

1. When stripping C.R.R. pipe, first pull the pins or back-out screws that hold the snap ring in place. If this is not done first, the producer runs the risk of damaging the spigot end or the header.
2. Have a man watch the vibrators and clips and wedges so they don’t work loose during the pour.
3. When oiling molds, keep oil off the ladder on the mold. There should be no opportunity for workers to slip while climbing a ladder.
4. Also, when oiling molds, keep the cage reinforcement away from the area. Form oil won’t help the bond of concrete to the cage.
5. If there is a leaking of "fines" at the gates or at the base, be sure to chick the gaskets.
6. Use a spreader beam to pick up and move molds. For proper handling of the mold, the cables coming from the spreader beam to the lifting lugs on the mold should be directly above them, or in toward the inside form. It is not a proper practice to have these cables set beyond the O.D. of the mold.
7. If the inside form has trench jacks in it, these should be extended to a snug fit against the inside of the core. This should be checked before the tamping top is put into place.
8. After the snap ring screws or the pins have been backed out of the C.R.R. header, use the jacking screws to break the top ring from the shoulder of the spigot of the pipe.
9. Before storing molds at the completion of a job, be sure to repair, clean and oil them. They will then be able to be put "on the line" as soon as they are needed.
   

Proper handling procedure illustrated, showing a crane with a spreader beam.

DON’TS

1. Don’t use a concrete bucket or a large sledgehammer to get the tamping top down into place. If this has to be done, the producer should find out why the top won’t go in easily, and then correct the problem.
2. Don’t beat on the lip of a base to get it to drop out of a pipe. Check the base, see what causes the problem, and correct it. It could be as simple as a lack of oiling before the pour.
3. Don’t let vibrators get caked with concrete. A pad made from a piece of a conveyor belt attached to the form above the vibrator does a good job.
4. Don’t over-vibrate. This will tear the mold apart and possibly damage the vibrator.
5. When setting the form on the base, don’t let it sit on the rubber, as this will cut the gasket. The form should close around the gasket, and core should expand out against the gasket.

Improper handling and storage of forms causes dents and deformation.

Proper care and maintenance of wet cast equipment is more a matter of common sense than anything else. It does not involve highly technical or sophisticated procedures. Generally speaking, the equipment can provide years of service at minimal cost, providing due attention is given to the above practices. Producers invest considerable money in wet cast equipment. Therefore, it is good management to see that it is properly used and maintained.

Posted 18 June 2001