3.4 BUTT FUSION WELDING

Size: px

Start display at page:

Download "3.4 BUTT FUSION WELDING"

Griselda Harrell
6 years ago
Views:

1 3.4 BUTT FUSION INTRODUCTION The butt welding proce conit of the joining of two component (pipe and/or fitting) of equal diameter and thickne in which the urface to be welded are heated until melting by contact with a heating element and then, after it removal, are axially (butt) joined by preure welding. Like Polyfuion and Electrofuion, with butt fuion welding there i no additional contribution or ue of filler material (i.e. welding rod or flux) required to complete the weld. The intruction below are for guidance only. Unlike ocket fuion, butt fuion welding implie that the operator are uitably trained on the ue of pecific welding machine to be ued and have a thorough knowledge of the procedure to be performed. Training i machine-pecific, a many detail will vary baed on pecific machine ued. ATTENTION! Each manufacturer of BUTT FUSION equipment publih hi/her own reference literature baed on the working parameter of the equipment produced. The uer SHALL REFER to thi pecific literature for every detail not exprely tated and for any reference information regarding the equipment RECOMMENDATIONS AND WARNINGS To perform a proper fuion procedure and enure a reliable joint, it i neceary to remember the following tep: The working temperature of the heating element hall be checked uing a calibrated contact thermometer. Thi meaurement hall be done after about 10 minute after the nominal temperature i reached, allowing the heating element to heat up evenly over the entire ection. Check the urface of the heating element (integrity of the non-tick layer) and properly clean it by uing oft paper or cloth, free of fiber. Check for the proper functioning of the welding machine. Check the efficiency of the clamp upport of the welding machine o that the correct alignment of the piece to be welded and the parallelim of the urface touching each other are enured. Check the drag force of the movable trolley, both a friction and in relation to the load being handled (pipe and/or fitting). Check the efficiency of the meauring equipment (preure gauge and timer). Check that the pipe and/or fitting to be welded are of the ame diameter and the ame thickne (SDR). The planing tool provided with the welding machine hall plane and align the pipe and fitting frontally and alo aborb the preure developed during the welding proce without deforming the welding point irreveribly. The welding machine hould be prepared for ue according to the manufacturer intruction. PP-RCT Piping Sytem 65

3.4.3 BUTT FUSION PROCEDURE PREPARATION FOR Cleaning the urface Before poitioning the part to be welded, clean the welding area to remove any dut, greae or dirt.

The poibility of axial movement without ignificant friction hall be enured by uing roller or ocillating upenion to allow the pipe liding to remove any mechanical tre from the clamp reulting from the

2 3.4.3 BUTT FUSION PROCEDURE PREPARATION FOR Cleaning the urface Before poitioning the part to be welded, clean the welding area to remove any dut, greae or dirt. Locking the end The pipe and/or fitting mut be locked in the clamp of the welding machine o that the contact urface to be welded are aligned between them. The poibility of axial movement without ignificant friction hall be enured by uing roller or ocillating upenion to allow the pipe liding to remove any mechanical tre from the clamp reulting from the weight of the locked pipe. The pipe and/or fitting hall be poitioned o a to contain the mialignment within 10%. To obtain thi reult, rotate at leat one of the element until the mot favorable coupling condition i reached and/or the locking force exerted on the fatening ytem of the clamp i not exceive a it could damage the urface of the component. 66 PP-RCT Piping Sytem

Milling the edge to be welded The end of the two component to be welded hall be planed to enure adequate plane parallelim and to remove any trace of oxide.

3 Milling the edge to be welded The end of the two component to be welded hall be planed to enure adequate plane parallelim and to remove any trace of oxide. The planing operation hall be carried out by bringing the part cloe to each other only when the milling cutter inerted between them i working and by exerting gradual preure uch a not to top the tool and prevent exceive heating of the urface in contact. The planing chip mut be formed continuouly on both edge to be welded: otherwie, invetigate the caue and repeat the proce until the required reult i reached. The planer mut be turned off only after the removal of the end to be welded. After the planing procedure i finihed, planing chip hall be removed from the inner urface and the urrounding area of the element to be welded, by uing a bruh or a clean cloth, free of fiber, fluff and lint and not ynthetic, oaked in a uitable cleaning liquid (e.g. iopropyl alcohol, trichloroethane chlorothene). Do not ue any olvent uch a gaoline, denatured alcohol or trichlorethylene. The planed urface hall not be touched or otherwie contaminated. At the end of thi phae, by bringing the two end into contact, the pace between the two edge mut not exceed the value of 0.02 inche (0.5 mm), a value that i half way between 1/64th of an inch and 1/32nd of an inch (which i difficult to meaure, but can be etimated by checking uing the width of a heet of tandard thin 20 pound paper). The value referenced above i lightly le than the thickne of tandard 20 pound paper). PP-RCT Piping Sytem 67

PROCEDURE Welding procedure by mean of contact heating element The butt fuion welding of pipe and/or fitting by mean of contact heating element hall be carried out following the different tep of the

4 PROCEDURE Welding procedure by mean of contact heating element The butt fuion welding of pipe and/or fitting by mean of contact heating element hall be carried out following the different tep of the welding procedure hown in the Figure below. In particular: Phae 1 : Approaching and preheating Phae 2 : Heating Phae 3 : Removing the heating element Phae 4 : Reaching the welding preure Phae 5 : Welding Phae 6 : Cooling Preure Legend 1 Phae 1 : Approaching and preheating 2 Phae 2 : Heating 3 Phae 3 : Removing the heating element 4 Phae 4 : Reaching the welding preure 5 Phae 5 : Welding 6 Phae 6 : Cooling Time PHASES Phae 1: Approaching and preheating Place the heating element on the welding machine, taking care to inert it properly in order to enure it tability on the upport of the machine bae. Place the edge cloe to the heating element and apply the initial welding force [preure (P1 + Pt)] for a time t1 and wait until the bead ha reached height h on both welding edge, a hown in Table 2 (page 70, 71). 68 PP-RCT Piping Sytem

Phae 2: Heating Once the bead ha reached height h, the contact preure between the edge and the heating element i reduced to a low enough preure to inure contact with the heating element during the

Phae 3: Removing the heating element Remove the heating element, making ure not to damage the edge of the two part to be welded. The removal mut be rapid to avoid exceive cooling of the heated edge.

The maximum allowable changeover time varie according to wall thickne a hown in Table 2. Phae 4: Reaching the welding preure Once the heating element ha been removed, bring the edge into contact.

Reaching the final welding force [welding preure (P5 + Pt)] mut take the amount of time t4 hown in Table 2.

5 Phae 2: Heating Once the bead ha reached height h, the contact preure between the edge and the heating element i reduced to a low enough preure to inure contact with the heating element during the heating phae. Keep the part in contact with the heating element for the time t2 (Table 2). Phae 3: Removing the heating element Remove the heating element, making ure not to damage the edge of the two part to be welded. The removal mut be rapid to avoid exceive cooling of the heated edge. The Changeover Time t3, i reported in econd, i the amount of time from the removal of the heating element to the contact with the edge (phae 4). The maximum allowable changeover time varie according to wall thickne a hown in Table 2. Phae 4: Reaching the welding preure Once the heating element ha been removed, bring the edge into contact. Gradually increae preure until the value (P5 + Pt) (phae 5) i reached o a to prevent exceive leakage of melted material from the edge in contact. Reaching the final welding force [welding preure (P5 + Pt)] mut take the amount of time t4 hown in Table 2. Phae 5: Welding Keep the edge in contact under preure (P5 + Pt) for a time t5, expreed in minute, a hown in table 2, unle the welding i performed in-line (e.g. on a pipe rack, on pipe hanger, performed on a vertical line, etc.) in which cae the full welding time t6 mut be oberved while the pipe are clamped. Phae 6: Cooling Once the welding time i over (phae 5), the welded joint can be removed from the welding machine, without being ubjected to ignificant tre. Allow the welded joint to completely cool to ambient temperature. PP-RCT Piping Sytem 69

6 3.4.4 BUTT FUSION PARAMETERS TABLE 2: BUTT PARAMETERS FOR NIRON PP-RCT PIPING SIZE OF PIPE SDR BEAD SIZE INCHES, h HEAT SOAK SECONDS, t2 MAX CHANGE OVER, t3 REACH FULL WELD PRESSURE, t4 NORMAL t5 2" (63 mm) / ½" (75 mm) / " (90 mm) / " (110 mm) / " (125mm) / " (160 mm) / " (200 mm) /16-3/ " (250 mm) /16-3/ " (315 mm) / " (355 mm) / IN-LINE t6 2" (63 mm) / ½" (75 mm) / " (90 mm) / " (110 mm) / " (125mm) / " (160 mm) / " (200 mm) / " (250 mm) /16-3/ " (315 mm) /16-3/ " (355 mm) / " (63 mm) / ½" (75 mm) / " (90 mm) / " (110 mm) / " (125mm) / " (160 mm) / " (200 mm) / " (250 mm) / PP-RCT Piping Sytem

7 TABLE 2: BUTT PARAMETERS FOR NIRON PP-RCT PIPING SIZE OF PIPE SDR BEAD SIZE INCHES HEAT SOAK SECONDS, t2 MAX CHANGE OVER, t3 REACH WELD PRESSURE, t4 NORMAL t5 12" (315 mm) /16-3/ " (355 mm) /16-3/ " (400 mm) /16-3/ " (450 mm) / " (500 mm) / " (560 mm) /32-1/ IN-LINE t6 24" (630 mm) /32-1/ " (63 mm) / ½" (75 mm) / " (90 mm) / " (110 mm) / " (125mm) / " (160 mm) / " (200 mm) / " (250 mm) / " (315 mm) / " (355 mm) / " (400 mm) / " (450 mm) /16-3/ " (500 mm) /16-3/ " (560 mm) /16-3/ " (630 mm) /16-3/ Note: 1. Butt Welding of Niron PP-RCT i to be performed at a heating element temp of 410 o F ± 18 o F. 2. Cooling time repreent the time the pipe and/or fi tting mut be held clamped in the machine under preure after joining. 3. When welding i performed in a bench type etting, normal cooling time can be oberved. When welding i performed in place (e.g. up in the air or on pipe rack, then the full cooling time hown in the lat column titled In-Line Cooling mut be ued. 4. Inline refere to welding pipe while it i on hanger, on a pipe rack, or in a vertical poition. 5. In all cae, ubtantial preure or bending tre mut be avoided on the welded aembly until the full cooling time in the lat column i oberved. 6. The information in the chart above i for manual butt fuion machine. When uing a hydraulic machine, the welding preure to be ued (in place of the welding force) will depend on the pecifi c machine ued and the drag force required. Thi will vary by pecifi c hydraulic machine type. PP-RCT Piping Sytem 71

3 JOINING PROCEDURES

3 JOINING PROCEDURES 3.1 WELDING EQUIPMENT Suitable equipment complying with guidelines DVS2207 shall be used for a fast and efficient installation of PPR PIPING SYSTEM: 1) Welder 800 W - 220V AC 50 Hz