METHOD STATEMENT FOR WELDING OF PIPES

1. SCOPE This document provides the outline methodology for the welding process of HVAC pipes. 2.PURPOSE To define the responsibilities and documentation in compliance and verification controls for pipe welding. 3. DEFINITIONS 3.1 Welding:

A joining process that produces a coalescence of metals by heating them to the welding temperature with use of filler metals obtained from welding electrodes.

3.2 Base material:

For the scope of this procedure, the base materials are black steel pipes according to TS 301/3, DIN2448. The pipe material approved by Engineer shall be used.

1- Black steel pipes having diameter between 2’’-3’’

2- Black steel pipes having diameter of 6’’and 10’’ (for Headers) To weld both black steel pipes and fittings to each other will be used proper joint design as following

3- Black steel sheets and various sections will be used as base metal for fabrication of pipe supports.

Black Steel sheets of 3-10 mm thickness. Black Steel NPU 65 Black Steel NPU 50 Black Steel Angles of 40x40mm, 50x50mm and 60x60mm

3.3 Filler material:

The filler material approved by Engineer shall be used.

Electrod Model : Oerlikon or As Kaynak

Electrod Type : Rutile Ø2,5mm and Ø3,25mm

3.4 Welding Machine:

The following welding machines will be used in the project

Electric arc welding machine (455A/380V/3P) : 1 Pcs.

Electric arc welding machine (Turbo) (400A/380V/3P) : 1 Pcs

Electric arc welding machine (Inverter) (161A/220V/2P) : 2 Pcs

3.5 Joint:

The junction of members or the edge of members that are to be joined. Usually grooved in “V” shape or else

designed for welding.

3.6 Butt Weld:

A joint between two members that are aligned approximately in the same plane.

3.7 Fillet Weld:

A weld of approximately triangular cross section joining two surfaces at approximately right angles to each other.

3.8 Welding Positions:

Flat: Direction of welding depends on welder. Left to Wright or Wright to Left.

Horizontal: Direction of welding depends on welder. Left to Wright or Wright to Left.

Vertical: Direction of welding is to be from bottom to top.

Overhead: Direction of welding is to be from bottom to top in case of pipe welding.

3.9 Weld pass:

A single progression of welding along the joint. The result of a pass is a weld bead.

3.10 Root Bead:

The first pass in the weld without any weaving motion.

3.11 Hot Pass:

The weld pass which is executed immediately after the root pass.

3.12 Filler Passes:

The weld passes that follow the hot pass and fill the weld groove flush or almost flush with the surface of the

base materials.

3.13 Cover Pass:

The weld pass that finishes the welded joint. The cover bead is little bit higher that the adjacent surfaces and

overlaps the groove.

4. WELDING METHOD

4.1 Welding Processes

Welding processes intended to be used: Shielded Metal Arc Welding-SMAW (Stick Welding)

4.2 Welders

All pipe welds will be executed by qualified welders and their certificates will be submitted separately.

4.3 Welding Operation

• Cut pipes to required dimensions. Prepare the edges of joint by providing groove of an angle of 30o-45o for all diameters ≥21/2” (See figure below).

• Clean the edges from rust, dirt, sparkles and primer by means of power grinding. • Fit-out the pipe line with temporary tag welds as per routes given in drawings. Provide 1 to 2 mm

clearance between pipes. • Fix the pipe line in place by means of hangers and clamps. • Prior to execution of root bead remove the temporary tag welds. • Set the welding machine to required ampere according to thickness of base materials. • Execute the root pass, • Execute the hot pass, • Execute the filler passes, • Execute the cover pass, • After completion of each pass remove deposited welds by power tools. • The number of passes depends on the thickness of base material and diameter of welding electrode

being used. • Apply 1 pass for pipes having diameter <4” by using Ø2,5mm electrode. • Apply 2 passes for pipes having diameter ≥4” by using Ø3,25mm electrode for root pass and Ø2,5mm

electrode for cover pass. 5.0 CONTROL OF WELDING CONSUMABLES

• Welding electrodes will be supplied in packs of shrink-film paper boxes. • Welding electrodes will be stored in their original packing. • Welding electrodes will be kept dry and clean. • In case of cold weather welding the electrodes will be oven heated prior to use at site and shall be kept

in quivers. 6.0 INSPECTION Inspection and testing will be done visually and suspicious joints will be subject to dye-penetration test as necessary. The pipe line is to be hydro tested as per plumbing code.