【 Weak current College 】 water supply pipe construction supervision of the

In recent years, China has always attached great importance to the development of new pipes and application, prohibit or restrict the use of certain metal pipe, application of new pipes has become an increasingly widespread. In promoting the use of pipe material, mainly for all kinds of plastic tubing. But due to some new tube no design and construction of the acceptance of national specifications, the use of easy problems, based on the experience of construction supervision, construction of water supply pipes in the summary of the project in the following few questions.
In recent years, China has always attached great importance to the development of new pipes and application, prohibit or restrict the use of certain metal pipe, application of new pipes has become an increasingly widespread. In promoting the use of pipe material, mainly for all kinds of plastic tubing. But due to some new tube no design and construction of the acceptance of national specifications, the use of easy problems, based on the experience of construction supervision, construction of water supply pipes in summing up the supervision should note the following issues:

1. the selection of the water supply pipe
Water supply pipe of high chemical stability, corrosion resistance, smooth surface, can effectively prevent the pipeline corrosion and fouling. This stage common water supply pipe mainly PVC pipe (UPVC), high-density polyethylene (HDPE), polypropylene pipes (PP-R, PP-C), polybutene (PB), acrylonitrile-butadiene-styrene (ABS), cross-linked polyethylene pipe (PE-X), etc. Their common benefit is non-toxic, health, long life, wall smooth, low head loss, corrosion-resistant, non-scaling, environmental protection and energy saving, light weight, easy installation. But there are shortcomings and deficiencies, such as linear expansion coefficient, anti-ultraviolet poor, small pipe overhead span, supporting point, some tubes produced higher. The main advantages and disadvantages of various pipe as follows:
1.1 PVC pipe (UPVC)
Advantages: high impact resistance and chemical resistance properties, corrosion-resistant hard texture, non-scaling, easy installation, low-cost;
Weaknesses: poor shock, during use, UPVC monomers and additives exudate, does not apply to hot water transportation, joint bonding technology requires a relatively high, the curing time will be longer.

1.2 high-density polyethylene (HDPE)
Advantages: it is currently the best pipe shock resistance, good toughness, good fatigue strength, heat resistance good resistance, impact resistance, high strength, light weight, the service life of up to 50a;
Disadvantages: Fusion need electric power, mechanical connection, connection pieces.

1.3 modified polypropylene tube (PP-R)
Benefits: has good impact resistance, heat resistance and resistance to creep capacity;
Disadvantages: in the same pressure and temperature, the most thick pipe wall, the linear expansion coefficient, anti-ultraviolet poor.

1.4 polybutene (PB)
Advantages: high temperature resistance performance good, the 20-95 ℃ long-term safe use, can withstand high loads without deformation, creep resistant, high flexibility;
Disadvantages: at present, no PB resin raw materials, to rely on imports, higher prices;

1.5 acrylonitrile-butadiene-styrene (ABS)
Advantages: high strength, impact resistance, without electric corrosion and soil corrosion;
Weaknesses: poor resistance to UV rays, adhesive curing time is long.

1.6 cross-linked polyethylene pipe (PE-X):
Advantages: good temperature resistance, high hardness, excellent creep resistance;
Disadvantage: you can only use metal fittings connections, you cannot recycle reuse.

2. material of entry and inspection
In order to guarantee the quality of the project, before approaching each batch of material requires the construction units to fill in the entry forms, supervision according to specification (GB50242-2002) on the venue material varieties and specifications, appearance, etc. for acceptance, the packing should be intact, surface scratches and external impact damage, the whole appearance of the root canal, no color should be smooth and are not, check the pipe wall thickness and roundness. Identification of the manufacturer of the product certification, quality inspection reports and Government authorities issued licences, and other quality certificates, to meet the requirements to be checked after the parades. Material entry, press the volume and frequency on the venue of materials and accessories for witness sampling, testing, without proof of inspection shall not be permitted before the contractor. Supervision in the witness of sampling, pay particular attention to the production lot number, because the production process of some unforeseen factors, same manufacturer, same raw material, the same recipe and technology, the different production batches of the product quality vary.

3. supervision of the construction process
As many of the water supply pipe is still in the promotion phase, construction personnel on a construction craft master is not in place, and these new pipes on construction personnel require high technical level, construction difficult. Therefore, the construction personnel training has become particularly important. Supervision on site inspection in particular pay attention to the pipe connections, most prone to leakage drinking water pipe, tube rupture is pipe connections. Water pipes are connected mainly with hot-melt Adhesive connections, or fused connection, special pipes connection and flange connection, attention should not be on the set of wire plastic pipe. Now on several major points of connection methods are summarized as follows:
3.1 adhesive connections
Using adhesive connections have water supply pipe UPVC pipe, ABS pipe. Pipes, pipe fittings and adhesives should be determined by the same manufacturers supporting supply, at this stage, no adhesive censorship in General, supervision should carefully check the adhesive quality certificate file and the conditions of use. In brushing adhesive, sand the bonding surface damage, with a dry cloth, Sassafras NET will be bonded surface dust, water, oil, when surface oil, cotton soaked in acetone cleaner Sassafras NET. Brushing adhesive, note dosage, not too much or too little, or affect the adhesive strength, spigot brushing adhesive, looking for direction will gently insert the pipe, the insertion depth socket should be consistent with the requirements, and ensure the socket interface of straightness and interfaces in the correct position. Ensure the adhesive interface quality of interfaces is the key to the surface by the damage, glue coating evenly, dosage, as required, plug theEntrance to the required depth.

3.2 hot melt or fused connection
Using hot-melt or fused connection of water pipe have PE pipe, pipe-pp-r pipe, PB. You should use the manufacturers to provide specialized welding tools, connection, you should clean the tube connection position and pipe fittings, guaranteed clean, dry, oil free, within the pipes and fittings made mark, fusion temperature to periodically check to ensure that the correct value, Fusion should prevent pipe fittings and tubing outward sliding, rotating, after heating is strictly forbidden to comply strictly with the hold time and cooldown.

3.3 card set (hoop) dedicated pipe connection
Use card set (hoop) dedicated pipe connection of water pipe have PE-X tube. Cutting pipe to ensure cut straight, tidy, no burrs, connect two tube port should be smooth, seamless, Groove should be uniform, pipe clamping bolts should be straight after, hoop installation should be conducted. Pipeline system after installation should pay attention to the finished product protection, never foot car pressure, to transfer to the subsequent jobs, transfer procedures clearly, particularly in embedded into the room or floor surface of the pipe, the sign must be done well, so that subsequent jobs or destroyed when the second decoration, prevent any damage to the pipeline. Pipe pressure test should strictly follow the specifications in order to ensure the normal work reliably.