Ⅰ 、Constructing Method of UPVC/CPVC Pipes

UPVC/CPVC piping systems are bonded by special cement. Hereunder are the steps:

 

 

1、Cutting

Power Saw and plastic tubing cutters can be used for pipe cutting. Cut the pipes as squarely as possible to provide maximum bonding area.

 

2、Deburring

Burrs must be removed from the inside, as well as the outside, of the pipe ends by pliers, filer and sandpaper on both inner side and outside of the cutting edge so that pipes and fittings are bond tightly.

 

3、Marking

Making marks on all pipes according to the length & depth of fitting parts. It can be used to ensure the pipe completely bottomed into the fitting during assembly.

 

4、Solvent Coating

Bonding surface should be softened by detergent, and then coat cement on both sides of bonding parts evenly.

 

Standard Volume of Cement

Nominal Outside Diameter （mm）	20	25	32	40	50	63	75	90	110	125	140	160
Cement Volume（g/piece）	0.40	0.58	0.88	1.31	1.94	2.97	4.10	5.73	8.43	10.75	13.37	17.28

 

5、Assembling

After coating cement, insert pipe into fitting socket while rotate the pipe a quarter turn. Pipe must bottom completely to the fitting stop. Hold the assembly part for 10-15 seconds to ensure initial bonding (2 persons work together to bond pipes larger than 6”). A bead of cement should be evident around the pipe and fitting juncture. If this bead is not continuous around the socket shoulder, it may indicate that insufficient cement was applied. If insufficient cement is applied, the joint must be cut out, discarded and begun again. Cement in excess of the bead can be wiped of with a rag.

 

Ⅱ、Hydrostatic Pressure Testing Notification of UPVC/CVPC Pipes

 

1、Cemented pipes must be tested 48 hours after installation. If pipes are installed underground, the test must be done after the trench is backfilled.

2、Support to tees, elbows, and fitting stops in the end must be stable. Thrust block made of concrete must be cured completely before test.

3、The end of the system should be blocked. Then, the system must be filled slowly with water, venting air from valves at piping run ends and at elevations during the filling process.

4、After the system is filled with water, make watertight test.

5、Hand pump or electro pump is used to rise up the pressure. The process must be slowly, more than 10 mins.

6、After rising up to the test pressure, hold it for 1 hour to check if there is leakage. If the pressure lowers down, rise up the pressure again. Within 15mins, if the pressure lowers smaller than 0.05MPA, the result is qualified.

 

Ⅲ、Constructing Method of PPR/PPH /PVDF Pipes

PPR/PPH/PVDF piping systems are bonded by heating. Hereunder are the steps:

 

1、The process requirement of hot melt socket welding

 

 

① Cutting & Deburring

Power Saw and plastic tubing cutters can be used for pipe cutting. Cut the pipes as squarely as possible to provide maximum bonding area and keep it clean without oil. Burrs must be removed from inside, as well as the outside, of the pipe ends by pliers, filer and sandpaper on both inner side and outside of the cutting edge so that pipes and fittings are bond tightly.

 

② Marking

Making marks on all pipes according to the length & depth of fitting parts. It can be used to ensure the pipe completely bottomed into the fitting during assembly.

 

③ Heating

Guide the pipes into heater straight to the marked assembly depth. In the meanwhile, push the fitting onto the heater and reach the marked depth.

 

④ Assembly

Heating time must be complied with the values in the under table. After heating time, remove pipe and fitting from the heater immediately and assemble them to the marked depth straight so that there is even bulge is the assembly place. Within the working time, tiny adjustment can be made but rotation must be prohibited. Keeping pipe and fitting from being wrenched, bent, and stretched.

 

Nominal Diameter（mm）	Heating Depth（mm）	Heating Time（s）	Assembly Time （s）	Cooling Time（min）
20	14.0	5	4	2
25	15.0	7	4	2
32	16.5	8	6	4
40	18.0	12	6	4
50	20.0	18	6	4
63	24.0	24	8	6
75	26.0	30	8	8
90	29.0	40	8	8
110	32.5	50	10	8

PS: If the environment temperature is lower than 5℃, extend heating time by 50%.

 

2、The process requirement of hot melt butt welding:

 

① The five stages of hot melt butt welding:

Pre-heating stage; Heating stage; Transfer stage; Welding stage; Cooling stage.

 

② Preparation before welding. The following preparation should be carried out before welding:

A) It should have a good climate environment in welding area.

B) The tools must be clean and the welding area must free of grease.

C) Connect all parts of the welding machine correctly, and clean the oil-way; Measure the supply voltage of electricity to confirm that the voltage meets the requirements of the hot melt butt welding machine.

D) Heating, cooling time and heating component temperature shall be set correctly according to the welding process. The hot plate of the first welding port shall be preheated for 10min at the welding temperature.

 

③ Clamp pipe/fittings

Assemble the two welding components on the hot melt butt welding machine, use holder to flatten the pipe (fittings), adjust the concentricity, adjust the two pipes (fittings) at the same axis, check the alignment, the displacement value of welding side shall not exceed the allowed tolerance, 0.1* the thickness of the pipe or the outer wall thickness of the plate.

 

④ Cut the welding side

The maximum width of the gap between welding sides after cutting must meet the requirements in table 1 and table 2 which as below:

 

Table 1 the maximum width of the gap between welding sides of PP pipe, fittings and plate after cutting.

Nominal O.D. of pipe（dn）	Width of the gap	Width of the plate B
dn≤355	0.5
400＜dn≤630	1.0	≤1500
630＜dn≤800	1.3	1500＜B≤2000
800＜dn≤1000	1.5	2000＜B≤2300
dn＞630	2.0	2300＜B≤3000

Unit：mm

 

Table 2 the maximum width of the gap between welding sides of PVDF pipe, fittings and plate after cutting.

Nominal O.D. of pipe（dn）	Width of the gap	Width of the plate B
dn≤355	0.5
400＜dn＜630	1.0	≤1500
400＜dn＜630	1.3	1500＜B≤2000
400＜dn＜630	1.5	2000＜B≤2300
400＜dn＜630	2.0	2300＜B≤3000

Unit：mm

 

⑤ Adjust the pipes (fittings) at the same axis

Check the welding sides of pipe or fittings which have no uneven milling, big gap or other defects. If it meets the requirements, adjust the pipes (fittings) at the same axis.

 

⑥ Test and check drag pressure

The frame of closing machine pressing evenly and slowly, when the frame starts to move, the recorded pressure value is drag pressure (pt), which is not fixed and must be measured every time when it is welding. The gap of welding side of pipes and fittings must less than 0.3mm; the displacement value of welding parts must be less than 10% of the thickness of welding parts.

 

⑦ Heating the welding sides stably

When the temperature of the heating component meet set temperature requirement, then assemble the heating component on the hot melt butt welding machine, keep the pressure and complete specified flanging formation time or flanging size, the pipes or fittings can’t interrupt touch with the heating component, meanwhile adjust the pressure to meet required butt welding heating pressure, and keep heating to meet the heating time’s requirement. Lowering the pressure to drag pressure (pt) and start heating timing, the heating tools must fit with welding sides tightly without any gap.

 

⑧ Transfer and butt welding

After the heating, pull the pipe or fitting out from the heating component, and joint the welding sides of pipes or fittings quickly, and increase the pressure uniformly to the total hot melt butt welding pressure (p1), high-pressure collision is strictly prohibited.

When aligning, put the welding sides on the hot iron until the whole side full touch the hot iron completely, side to side, and it can observing the flanging formation. When the flanging height around the entire circumference of the tube or the entire top of the plate upto the required value, then it's aligned.

 

⑨ Connector cooling

After hot melt butt welding, the connector shall be fixed in the hot melt butt welding machine, and cooling the connector according to cooling period which specified in the regulations of pressure maintaining and cooling of hot melt butt welding machine.

 

⑩ Remove pipe/fittings

After the cooling, reduce pressure to zero, and then remove the welded pipe/fittings.

 

Hot melt butt welding process reference table of PPH pipes and fittings

Nominal wall thickness/MM	Aligning	Heating	Transfer	Welding
	Heating component temperature 210℃±10℃
	Flanging height of heating element after End of alignment time （min） (Alignment p=0.01N/mm2)/mm	Heating time≈10e+40s (Heating p≤0.01N/ mm2)/s	Switching time（max）/s	Welding pressure formation time/s	Cooling time under welding pressure (min) 【p=(0.10+0.01)N/ mm2】/min
6.0～7.0	0.5	135～175	5～6	6～7	6～12
7.0～12.0	1.0	175～245	6～7	7～11	12～20
12.0～19.0	1.0	245～330	7～9	11～17	20～30
19.0～26.0	1.5	330～400	9～11	17～22	30～40
26.0～37.0	2.0	400～485	11～14	22～32	40～55
37.0～50.0	2.5	485～560	14～17	32～43	55～70

 

Hot melt butt welding process reference table of PVDF pipes and fittings

Nominal wall thickness/MM	Aligning	Heating	Transfer	Welding
	Heating component temperature 210℃±10℃
	Flanging height of heating element after End of alignment time（min） (Alignment p=0.01N/mm2)/mm	Heating time≈10e+40s (Heating p≤0.01N/ mm2)/s	Switching time（max）/s	Welding pressure formation time/s	Cooling time under welding pressure （min） 【p=(0.10+0.01)N/ mm2 t≈1.2e+2min】/min 【p=(0.10+0.01)N/ mm2 t≈1.2e+2min】/min
6.0～10.0	0.5～1.0	95～140	4	5～7	8.5～14
10.0～15.0	1.0～1.3	140～190	4	7～9	14～19
15.0～20.0	1.3～1.7	190～240	5	9～11	19～25
20.0～25.0	1.7～2.0	240～290	5	11～13	25～32

 

Ⅳ、Hydrostatic Pressure Testing Notification of PPR/PPH /PVDF Pipes

 

●　Hydraulic test has to be performed sectional; tested length should be no longer than 500m.

●　Before test, make sure pipes are fixed, joints are not covered, and the whole system is independent from water outlet tools.

●　Pressure gage with tolerance 0.01Mpa needs to be installed in the lowest place of the system.

●　Fill water from lowest part of the system to remove the air and make watertight test.

●　Hand pump or electro pump is used to rise up the pressure. The process must be slowly, more than 10 mins.

●　After rising up to the test pressure, hold it for 1 hour to check if there is leakage. If the pressure lowers smaller than 0.06MPA, the result is qualified.

●　Hold the pressure 1.15 times of the working pressure for 2 hours. If the pressure lowers less than 0.03MPA, the result is qualified.

●　There must be no leakage in the system during test.

●　During 30 mins, if the pressure lowers down, it is allowed to raise up the pressure again 2 times.