1. Drainage pipe fittings are not flowing downstream.
No downstream fittings are used at the elbow and tee, which increases the water flow resistance. Or the water from the two outlets of the drainage horizontal pipe flows in opposite directions to the tee between the two outlets and is discharged from the side socket of the tee. The disadvantage is not only that the water flow is not smooth, but the slope of the pipe section is unreasonable and easily blocked. It is advisable to change this “head T” approach to elbow plus water tees (whether it is changed to Y tee or TY tee) and stagger to avoid that the drainage of different directions meets orthogonally on the plane.

2. There is no gap in the flexible connection of cast iron pipe joints.
The process stipulates that there should be a gap of about 10mm between the sockets to facilitate expansion and contraction. In the operation, this point is often ignored and the sockets are pressed to death. Marks should be made in advance to ensure that there is a gap.

3. Common problems with floor drain.
The use of unqualified floor drains with a water seal height of less than 50mm is likely to cause drying and blockage, and loss of odor barrier function. Qualified products should be used, and for further reliability, a trap should be added under the floor drain.
The bell-shaped floor drain is used too much, and it is used in public toilets, large kitchens, and sinks in canteens. These places have a lot of scum, which is easy to block, and often needs to be washed. It is recommended that public toilets use grills and traps; large kitchens use drainage trenches and grills; canteen sinks add movable grid slag to make traps to isolate odors and add oil traps; bathrooms and kitchens should use net-frame floor drains; The floor drain is not required in the family kitchen.
If the floor drain is installed too high, it will affect the drainage function; if it is installed too low, it will affect the appearance of the ground. Before installing the drain socket, the floor drain specification and the thickness of the ground decoration layer should be accurately understood, and the reasonable elevation of the drain socket should be calculated.

4. The quality of the pipeline connection.
The pipe is poorly cut, the cut is uneven, and there are skew, bumps, and burrs. According to the process regulations, the pipe should be leveled before cutting, and the cutting line should be drawn for the large pipe. After cutting, the burrs should be removed, and the inner diameter should be shredded due to extrusion.
Poor thread openings, crooked, messy, or broken threads; too tight or too loose threads, affecting tight connections; leaving too few exposed thread openings after connection, and turning to the end, so that there is no room for tightening when water leaks. Such errors must be corrected according to the requirements of the operating process.

5. The problem of the reserved casing and iron parts.
The positions of reserved casings and iron parts on concrete beams, walls, and slabs are inaccurate, which is unfavorable for pipeline passage and bracket installation. The position should be calculated in advance, and the casing and iron parts should be spot welded to the main reinforcement when the steel is tied. Waste paper or loess should be stuffed inside the casing to prevent the cement from flowing in; the concrete should be supervised by special personnel to prevent the casing from moving. The upper mouth of the floor piercing casing should be 30-50mm higher than the floor surface to ensure that the groundwater behind the floor covering does not flow into the casing.