PVC drainage pipes are the "blood vessels" in the building drainage system. Its quality directly determines whether the drainage is smooth and whether the house is safe to use. The national standard, as the "quality pass" of the industry, is the core basis for judging whether PVC drainage pipes are qualified or not. So, what is the national standard standard for PVC drainage pipes? What are the key requirements that affect quality hidden in the relevant GB/T specifications? Today we will take these "technical codes" apart and make it clear.

At present, there are only two mainstream national standards for PVC drainage pipes and pipe fittings in our country - "Hard Polyvinyl Chloride (PVC-U) Drainage Pipes for Buildings" (GB/T 5836.1-2018) and "Hard Polyvinyl Chloride (PVC-U) Pipe Fittings for Buildings" (GB/T 5836.2-2018). These two standards were updated in 2018, replacing the old version of the specification, and are more in line with the current technical level and use scenarios.

First look at the material requirements - this is the "gene" of the pipe. The specification makes it clear that the residual amount of vinyl chloride monomer (VCM) in the PVC-U resin cannot exceed 1mg/kg, which is to prevent the hidden danger of harmful substances; the impact strength also has a hard index: do a drop hammer impact test at 0 ° C, and no more than 1 in 10 samples can be broken. After all, the temperature is low in winter, and if the pipe is cracked as soon as it is hit, it will be troublesome.

Then talk about the size deviation - this is the key to "fit". The deviation of the outer diameter of the pipe must be stuck between 0.3mm and 1.5mm (the larger the pipe diameter, the wider the deviation range), and the deviation of the wall thickness cannot exceed 10% of the nominal wall thickness. If the size is not accurate, the pipe and pipe fittings cannot be connected or not tightly connected, and water leakage is a matter of time.

Then there are physical properties - this is the guarantee of "manufacturing resistance". In terms of chemical resistance, the pipe is soaked in common chemical solutions such as hydrochloric acid and sodium hydroxide for 28 days, and it cannot crack or swell; heat resistance is more practical: 60 ° C hot water is soaked for 168 hours (that is, 7 days), and the ring stiffness cannot drop by more than 20%. After all, the kitchen and bathroom occasionally discharge hot water, so it must be able to withstand it.

also has inspection methods - this is the rule of "check". Each batch of goods should be randomly selected for 3 tests to check the appearance, size, impact strength, and ring stiffness. If one fails, it has to be doubled and checked again. If it fails, the whole batch has to be rejected to ensure that the goods leave the factory are reliable.

Finally, the identification requirement - this is the "ID card". The surface of the pipe must be clearly printed with the manufacturer's name, specifications (such as DN50, DN110), execution standard number (GB/T 5836.1-2018), and production date. If you don't have this information, it is either a small workshop product or a non-compliant product. Don't buy it.

In fact, these GB/T specifications are not "tightropes", but "umbrella company" - for manufacturers, it is the "manual" for production; for construction and supervision, it is the "ruler" for acceptance; for us ordinary users, it is the "guide" for choosing the right pipe. Follow the national standard, the probability of blockage, leakage and cracking of the drainage system can be reduced by more than half, and the house is more secure.

To sum up: The national standard for PVC drainage pipes is GB/T 5836.1 and GB/T 5836.2-2018. The core requirements cannot be bypassed by materials, sizes, performance, inspection and identification. To understand these, whether it is buying pipes or inspecting projects, you can have a bottom line in your heart.