Installation points of T-pipe
1. Clean debris within the groove of the T-type female end surface with wire brushes, 25mm putty grafters, brushes and rags. Check the chamfer angle of the other pipe socket, and keep the socket as well as the rubber ring clean.
2. Place the rubber ring into the groove of the female end. For the T-pipe below DN800, it is easy to install it if the rubber ring is kneaded into 8-type shape with the fingers; for the T-pipe above DN800, into three equal parts or quincunx.
3. Apply the lubricant on the inner surface of the rubber ring and the interface of the socket.
4. Check the rubber ring's position of the fitting joint and make use of a thin and narrow steel ruler to check the compression ratio of the rubber ring around the four 90 degree points of the socket.
Backfill of the pipe trench
1. Before backfill, remove ponding and clean debris remained in construction from the bottom of the groove. After confirming that the quality of the main bodies of
pipes and pipe joints are up to the specification, the pipe bodies shall be backfilled in time, and pipe joints shall also be backfilled after the pressure test.
2. The backfill material should be the good-quality sand soil without any debris such as the rubble, brick, garbage, etc., unless other backfill materials are specified.
3. In the backfill procedure, fully fill the bottom of the pipe first, especially the bottom of the pipe installed from the female end to the socket.
4. The backfill material shall be piled up in the axial direction, and then should be uniformly put from two sides of the pipe top into the trench until the backfill material reaches the pipe top.
5. In the backfill procedure, tamp the trench layer by layer. Below the center line, every 200mm is one layer of backfill. Above the center line, every 300mm is one layer of backfill. If it is 500mm over the pipe top, backfill can be done by small machinery, and 700mm over, it can be completed by the road roller.
6. When backfilling the trench with sand, you shall add water and then tamp it by the vibrating bar. The degree of tamping shall guarantee the pipe will not uplift.
7. There is working pits at the pipe joints, and you shall backfill the working pits first.
8. The most important thing in backfill is backfilling evenly, otherwise local subsidence will cause displacement of
ductile iron pipes. Backfill needs to be done carefully and uniformly, meeting the matters needing attention of compacted backfill according to design requirements.
