Construction standard

General regulations on construction

 1. The following conditions should   be satisfied before the pipeline is laying and installation.
 A. Full set of   drawing of laying and installing and technical documents should be ready with   the explanations one the above drawing and documents.
 B. The laying program   technique the supply of technical training of the pipelines laying and   installation
 C. The workers have passed the exam of technical training of   the pipeline laying and installation.

 2. The supplied pipes and fittings   with the instructions and quality certificates should be conformed to the design   standards

 3. The materials with any sign of damage are not permitted to   be used. If any problems of quality control are found the rechecking should be   done immediately.

 4. In course of the pipes laying and installation, the   pipes are open should be block order to avoid unnecessary waste.

 5.   Before the laying or installation of the pipelines, the pressure classifications   of cold-or-hot-water-supply pipes should be rechecked

 The laying and   installation of the pipelines

 1. If the pipes are laid in walls the   grooves should be reserved in advanced. Its depth should be De+20mm and width   De+40-60mm, if there are not size of grooves in the designed drawings. The   surfaces of the grooves should be flat without any sharp angles. It is possible   for the pipes of PP-R to make the walls break because of their expansion in hot   condition or shrinkage in cold condition when the pipes are being tested.   Therefore the more attention to the hot pipes should be paid.
 2. On the   installation the pipes can°￠t be distorted in direction of the axle. And on the   installation of the pipes passing through the walls and floors it is unsuitable   to correct them. When they are laid with other metal pipes in parallel, there   should be a distance at a minimum of 100mm. The metal ones should be laid in the   inside flank.
 3. The pipes of PVC-U: The pipe can be cut at where you would   like to fix either with a handsaw or a machine saw. But the both ends should be   kept smooth and flat. The sent us should be removed with a file. As for the   pipes of PP-R, they can be cut at where you would like to fix with a special   shear. The dirt covered with the pipes and fittings should be wiped out with   clean cotton fabric. And the inserting depth should be marked on them. The   connected ends must be clean, dry and un-greasy.
 4. Adherence of the pipes   and fitting: Before adherence the trial assembly must be done. And you clean   500mm. Of the surface of the inserted pipe. Next-you can insert the pipe into   the connected pipe and wait for 3 minutes. Then you should wipe out the glue   squeezed out of the connected joint. At this time turning of the pipes is   prohibited to avoid leakage.
 5. For pipes of PP-P the conducting wire   between the heat-melting and electric-melting fitting should be connected   correctly. The voltage of electric heating should be tested before connection.   The heating duration should be conformed to the regulations stipulated by the   factories. In the course of melting or cooling the removal or turning of the   pipe is prohibited. Any pressure must not be put on the pipe.
 6. After   adherence the connected section should be straightened axially.
 7. The   flexible joint part: There should be a gap between the end of the pipe and   flexible joint, 5-20mm. In winter.
 8. Installation of pipes inside room: the   installation should be done after the rooms have been whitewashed. And the   sleeves should be installed in walls in advance.
 9. The steel sleeves should   be installed 50 mm. above the floor if the pipes go through the floors. The   waterproof measures should be strictly taken and a fixed support should be set   up at the front end in order to avoid the deformation, and leakage of the pipes
 10. Fixation of pipelines: on installation the pipeline should be fixed with   pipe fasteners which are installed ever 1-2m, and the sling brackets should be   installed every 0.6m to prevent against natural deformation of plastics.
 11.   The pipelines should be far away from heat sources, The should be at minimum of   400mm. Away from the heat source and 200mm. Away from heating pipes.
 12. If   the hot-water-supply pipelines of PP-P go through any walls the steel sleeves   should be set to let the hot-water-supply flexible. If the cold-water-supply   pipelines of PP-R and PVC-U go through any walls the holes with the size 50mm.   Large than the outside diameter of the pipe should be reserved.
 13. For the   pipelines laid in the floors and walls, the minutes of the tested pressure and   checking before acceptance should be written before the above pipelines are   covered.
 14. For the laying of the pipes leading into the building and the   pipes laid in the ground of the room, the following requirement should be   fulfilled.
 a. First to harden the soil;
 b. Then to re-dig the soil;
 c. It is not advisable to lay the pipes without hardening the soil;
 d.   The bottom of the ditch for the pipes should be flat without any sharp angles   and with the soil of granularity at a maximum of 12mm, if necessary; a 100mm.   Thick layer of sand may be laid on the bottom of the ditch.
 e. When the   ditch with pipes in it is backfilled there must not be any sharp and hard   substance that will touch the pipes. Firstly a 300mm, Thick layer of sands and   soil with a diameter at a maximum of 12 mm, should be backfilled to the ditch.   The depth of the ditch for the pipes laid in the rooms is at a minimum of 300mm.
 f. The protective sleeves should be set at where the pipes are out of the   floor with 100mm. Higher than the floor.
 g. The height from the sleeves to   the top of the reserved holes of foundation walls is at a minimum of 100mm, if   no special stipulations.
 h. The protective steps should be strictly taken if   the pipelines go through a street or road and the thickness of the soil covered   on the pipelines is at a maximum of 700mm. Test pressure

 The test of the   working pressure of the pipeline system of PP-R must be according to the   following regulations.
 1. The testing pressure should be 2 times as high as   the working pressure of the pipeline system, but at a minimum of 1.5Mpa.
 2.   The water pressure of the PP-R pipeline system should generally be tested 24   hours after the pipelines are joined and installed.
 3. Before the test of   the water pressure the protective measures should be taken. But the joint   section should be laid bare.
 4. The following steps should be taken.
 A.   To block the ends of the pipes and fill the pipes with water slowly and bleed   air out of the pipes.
 B. To check the water sealing after the above are   done.
 C. To raise the pressure slowly with a hand pump. The time duration of   raising the pressure must not be shorter than 10 minutes. The accuracy of the   testing instrument should not be below 0.01MPa.
 D. When the pressure is   raised to the set testing pressure, and after it is stabilized for 24 hours   testing pressure declines in the range of 0.06MPa.
 E. On condition of 1.15   times as high as the working and of 2 hours of stability the testing pressure   declines in the range of 0.03MPa. And at the same time the joint section should   be checked to guarantee that there is no leakage.
 F. The test of the   pressure of the pipes laid in the floors and walls should be done before the   civil engineering have been finished. REMARK: It is allowed to discharge or   raise the pressure to the testing pressure within 30 minutes twice. The test of   the pressure of the PVC-U pipe must meet the regulations of testing and checking   before acceptance.

 Rinse and disinfect
 1. Before acceptance of the   water-supply pipeline system the pipelines should be rinsed in advance. The   water flowing speed is at a minimum of 2 meters/second. On rinsing each of   faucets should be opened the lowest point of the system should be at the water   outlet How long the pipelines are rinsed depends upon the water quality at the   water outlet where the water quality is the same as that at water inlet.
 2.   After the drinking-water-supply pipelines are rinsed they should be disinfected   with free chlorine-free water which will be kept within them for over 24 hours.
 3. After the pipelines are disinfected they should be rinsed with drinking   water that must conform to the current national standard the sanitary of   drinking water. Otherwise the can not be used.