CN101112792A - PVC-M pipe hot melting and connecting method - Google Patents

Abstract

A PVC-M pipeline thermal fusion welding method, belonging to the pipe technical field, is used for solving the pipeline welding problem. The invention has the technical proposal that the thermal fusion welding of the PVC pipe is carried out on a thermal fusion butt welding machine and the steps are adopted that initial disposal and the pre-heating are carried out to the pipe material or pipe part to be welded, a butt head end surface is milled , a heating plate is heated to the temperature ranging from 210 DEG C to 230 DEG C, the die is closed, heating, pressurizing, and heat absorbing for 30 seconds through 120 seconds are carried out, the cooling time is for 10 minutes through 30 minutes, the pressure is reduced to zero, the die is opened, and the well welded pipe material or pipe part is obtained. The invention leads the connected pipeline into a whole with good sealing performance, high bearing capability, safety and reliable operation and is very suitable for the chemical pipeline which is not suitable for the rubber ring connection. The pipe part made of the invention overcomes the shortages of non-stability of production quality of the FRP composite pipe part and low bearing capability and at the same tine avoids the shortage of no corrosion resistance of the steel pipe parts.

Description

A kind of PVC-M pipe hot melting and connecting method

Technical field

The present invention relates to a kind of method of attachment of plastic conduit, particularly the hot melting and connecting method of PVC-M plastic conduit or pipeline section belongs to the tubing technical field.

Background technology

In thermoplastic, the characteristics of PVC-U PVC-U are intensity height, and fragility is bigger.Though therefore the minimum strength (MRS) of PVC-U material is more than 25MPa, its design stress is not high, and international standard is 10～12.5Mpa, and reason just is that fragility is bigger, otherwise just can not guarantee the projected life in 50 years.For this reason, people have carried out modification to it, by adding impact modifier in the PVC-U basic components, produce anti-impact type polyvinyl chloride MODIFIED PVC (PVC-M) tubing that has intensity and toughness concurrently.Being added in of impact modifier also kept the original intensity of material when having increased material ductility, therefore except that characteristics with common PVC-U tubing, PVC-M tubing also has excellent toughness and shock resistance, can resist the differential settlement of the slight scuffing, point load and the ground that produce in tubing installation and the transportation better; PVC-M tubing also can be resisted water hammer effect effectively, reduces the destruction of pipeline in transportation.

Along with the continuous expansion in PVC-M pipe applications field, the connected mode of common PVC-U tubing---elastic seal ring connects and can't adapt to.It is lower that the major defect of its existence is that resistance to plucking takes off ability, and in settlement of foundation serious area and non-excavation field, tubing is easy to deviate from from sealing ring, thereby can't guarantee the security of seal for pipe joints.

But, but being difficult to be applied on the PVC-M tubing with the common pipe welding method, this is because of the raising along with pipeline strength and toughness, its pipe thickness reduces greatly, in general, under the same application conditions, the wall thickness of PVC-M pipeline is approximately 20～30% of PVC-U.Because tube wall is thin, therefore, problems such as distortion, rosin joint, dry joint and misalignment appear in welding easily, have a strong impact on pipeline quality.

In addition, the heavy caliber pipe fitting corresponding problem of pipeline also is the bottleneck of puzzlement industry development always, at present a lot of composite glass steel pipe spares or metal tubes of adopting, and the former adopts the compound mode of PVC-U pipeline section and fiberglass to make, make the pipe fitting quality and be difficult for guaranteeing, cause potential safety hazard easily; Metal tube then have corrosion-resistant, with defectives such as the plastic conduit connection safety is not good.

Summary of the invention

The present invention is used to overcome the defective of above-mentioned prior art and a kind of PVC-M pipe hot melting welding method is provided, to solve the problem of PVC-M large diameter pipeline on connection is supporting.

Problem of the present invention realizes with following technical proposals:

A kind of PVC-M pipe hot melting welding method, it carries out join by fusion with polychloroethylene pipes on butt fusion welding machine, and adopts following steps:

A. tubing to be welded or pipe fitting are fixedly clamped on frame, the locked joints part is removed the dirt of two pipe joints and end;

B. preheating, preheat temperature are 25～35 ℃;

C. the butt joint end face carries out milling, makes its gap value be not more than 0.3mm;

D. check the tubing axiality, its maximum unfitness of butt joint is no more than 5% of tube wall thickness;

E. the temperature of heating plate on the welding machine is heated to 210～230 ℃, and guarantees that whole temperature of heating plate is even, then heating plate is placed on the frame closed anchor clamps;

F. heat the pressurization operation, initialization system pressure P 1=P0+ heated pressure, heating, pressurization;

G. the operation of absorbing heat is reduced to P2 with pressure, the P2=P0+ pressure that absorbs heat, and its numerical value is for dragging pressure, and omnidistance band is pressed heat absorption, and the heat absorption time is 30～120 seconds;

H. refrigerating work procedure is opened anchor clamps, takes off heating plate, the rapid closing anchor clamps, and evenly pressure is adjusted to P3, and the P3=P0+ cooling pressure begins to cool down, and be 10～30 minutes cool time;

I. pressure is reduced to zero, opened anchor clamps, take off and weld tubing or pipe fitting.

Above-mentioned PVC-M pipe hot melting welding method, described weld fusion pressure goes out flange, and the height of flange is 15～20% of a wall thickness.

Welding method provided by the invention, the pipeline that it connected becomes one, good airproof performance, the bearing capacity height, safe and reliable to operation, be highly suitable for being not suitable on the chemical pipeline of cushion rubber connection.With the pipe fitting that it is manufactured, overcome composite glass steel pipe spare quality of production instability, the shortcoming that bearing capacity is low; Also avoided the not corrosion resistant shortcoming of steel pipe fittings.

The specific embodiment

The welding equipment that the present invention uses is butt fusion welding machine, is not less than the connection of 200mm pipeline applicable to diameter, and the unfitness of butt joint of tubing is no more than 5% of wall thickness.

The concrete steps of welding are:

1. welding machine is connected power supply, voltage change is controlled at ± 10% in; Pumping plant and frame are connected with the hydraulic pressure lead, and the dirt of cleaning joint, in order to avoid dirt enters hydraulic system, damages hydraulic component; The locked joints part, joint has the danger that is opened when preventing high-pressure work.

2. tubing to be welded (pipe fitting) is fixedly clamped on frame, before the welding, removes the dirt of two pipe ends with clean cloth.During the welding large-diameter pipe, level up, with protection pipe and the frictional force that reduces in the welding process with support.

3. the welding condition by the PVC-M material is provided with heat absorption time and cool time.

4. the PVC-M pipe end is carried out preheating, temperature is in 30 ± 5 ℃ of scopes, and is special in the winter of cold, necessary preheating, and this is because the melt flow rate (MFR) cause littler than PE of PVC-M.

5. frame is opened, put into milling cutter and fixing.Start milling cutter, closed anchor clamps carry out milling to the end face of Guan Yu (pipe fitting).

6. when forming continuous smear metal, open anchor clamps, close milling cutter.

7. take off milling cutter, closed anchor clamps are checked the gap (gap value must not greater than 0.3mm) at pipe two ends.When frame is taken off milling cutter, should avoid the collision of milling cutter and end face, as milling again takes place; The end face that mills does not want that hand is touched or by pollutions such as greasy dirts.

8. check the axiality (its maximum unfitness of butt joint be thickness of pipe wall 5%) of pipe; When the gap of both ends of the surface and unfitness of butt joint can not meet the demands, weldment clamping again, milling were treated in reply, can carry out next step operation after qualified.

9. whether the temperature of checking heating plate suitable (220 ± 10 ℃), and make whole temperature of heating plate even.

10. test and register system drags pressure P 0.

11. the heating plate that temperature is suitable places on the frame closed anchor clamps, and the pressure P 1 of initialization system.The P1=P0+ heated pressure.

12. treat between pipe (pipe fitting) projection evenly, and flange height is when reaching requirement (seeing the welding condition table)

The technology sequence number	The contents of a project	Parameter area	Explanation
				1	Environment temperature, ℃	20 ± 5	The environment temperature that refers to the real work place herein.
2	The end face preheat temperature, ℃	225 ± 10	When environment temperature is lower than 20 ± 5 ℃, or tube wall thickness to be welded before the milling end face, need be treated welding end surface and carry out preheating during greater than 5mm.
				3	End face preheating time, s	30-90	According to environment temperature and tube wall thickness adjustment.

4	Heating-up temperature, ℃	225 ± 10
				5	Heated pressure, MPa	P ± 0.3	According to formula P=Л (dn-e) e * 0.97/S CylinderCalculate.
6	Heat time heating time, s	5-20	Select voluntarily according to the flange situation.
				7	The heat absorption time, s	30-120	Omnidistance band is pressed heat absorption.
8	Heat absorption pressure, MPa	P ± 0.3	According to formula P=Л (dn-e) e * 0.97/S CylinderCalculate.
				9	Welding pressure, MPa	P ± 0.3	According to formula P=Л (dn-e) e * 0.97/S CylinderCalculate.
10	Dwell time, m	2-10
				11	Cool time, m	20 ± 10

, pressure is reduced to P2 (be approximately and drag pressure), and absorbs heat, the opening entry heat absorption time; P2=P0+ heat absorption pressure (heat absorption pressure is almost nil).The fusion temp of PVC-M will exceed about 10 ℃ than PE.Welding pressure can not be too high, because the melt flow rate (MFR) of PVC-M is littler than PE, hypertonia causes cold welding and dry joint easily, influences welding quality, so the welding of PVC-M is much more difficult.

13. after arriving the heat absorption time, open anchor clamps rapidly, take off heating plate.

14. the rapid closing anchor clamps, and in official hour, evenly pressure is adjusted to P3, press button cool time simultaneously, be 10～30 minutes cool time; The P3=P0+ cooling pressure.Evenly boost after the anchor clamps closure, can not be too soon or too slow, should in official hour, finish, in order to avoid form dry joint, rosin joint; This process is the pressurize natural cooling process.

15. after arriving cool time, pressure is reduced to zero, open anchor clamps, pipe fitting promptly welds.

Because of tube wall is thinner, prevent distortion.Note taking off pipeline section after the cooling fully, do not give any external force of weld bond.Qualified weld bond should have two flange (flange), the welding bead turnup to the pipe internal and external circumference on, the shape of two flange, big or small uniformity, pore-free, bubbling and crackle, the root in the slit between two flange is not less than the surface of institute's welded tube.

Claims (2)

1. a PVC-M pipe hot melting welding method is characterized in that, it carries out join by fusion with polychloroethylene pipes on butt fusion welding machine, and adopts following steps:

A. tubing to be welded or pipe fitting are fixedly clamped on frame, the locked joints part is removed the dirt of two pipe joints and end;

B. preheating, preheat temperature are 25～35 ℃;

C. the butt joint end face carries out milling, makes its gap value be not more than 0.3mm;

D. check the tubing axiality, its maximum unfitness of butt joint is no more than 5% of tube wall thickness;

E. temperature of heating plate is heated to 210～230 ℃, and guarantees that whole temperature of heating plate is even, then heating plate is placed on the frame closed anchor clamps;

F. heat the pressurization operation, initialization system pressure P 1=P0+ heated pressure, heating, pressurization;

G. the operation of absorbing heat is reduced to P2 with pressure, the P2=P0+ pressure that absorbs heat, and its numerical value is for dragging pressure, and omnidistance band is pressed heat absorption, and the heat absorption time is 30～120 seconds;

H. refrigerating work procedure is opened anchor clamps, takes off heating plate, the rapid closing anchor clamps, and evenly pressure is adjusted to P3, and the P3=P0+ cooling pressure begins to cool down, and be 10～30 minutes cool time;

I. pressure is reduced to zero, opened anchor clamps, take off and weld tubing or pipe fitting.

2. PVC-M pipe hot melting welding method according to claim 1 is characterized in that described weld fusion pressure goes out flange, and the height of flange is 15～20% of a wall thickness.