Gouging Procedure 5ss2s
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Gouging Procedure
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Gouging Procedure
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Table of Contents
Page
1.0
INTRODUCTION
4
2.0
SCOPE OF WORK
4
3.0
DEFINITIONS
4
4.0
REFERENCED STANDARD AND SPECS
5
5.0
PROCEDURES
5
5.1 5.2 5.3
Electrodes Operating techniques Inspection
7 7 11
Table 1 - Suggested Current Ranges for Commonly Used Electrode Types and Sizes
8
Figure 1 - Typical Arrangement for the Carbon Arc Gouging (CAG)
6
Figure 2 - How a Standard CAG Torch Works
6
Figure 3 - Flat Position Gouging
7
Figure 4 - Vertical Position Gouging
9
Figure 5 - Horizontal Position Gouging
9
Figure 6 - Overhead Position Gouging
10
Figure 7 - Gouging Electrode push angle
10
Figure 8 – Cutting with CAG
11
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Doc Title:
1.
Gouging Procedure
Document No Date Page
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INTRODUCTION The offshore development shall consist of three identical wellhead platforms SPD12A, B, C each with 15 slots for field exploration located in approximately 70 m water depth, each linked to a remote flare platform through a two span bridges. Topsides design features shall be according to minimum production facilities concept consisting of fluid gathering, chemical injection, well testing, condensed and saturated water separation and oily water treatment. The platforms shall be designed for drilling through jack-up operations. All the three platforms shall be unmanned and personnel from shore shall perform major operations, whereas routine and emergency operations shall be carried out from nearby offshore complexes built within NIOC South Pars Phase-1 development. Personnel will come on board by boat or by helicopter on temporary basis and as such a shelter to accommodate 6 people on a temporary basis shall be included. Each wellhead platform shall be designed for maximum production capacity of 1200MMSCFD although the planned production shall be 1000 MMSCFD of equivalent well fluid. Each of the wellhead platforms shall have HP/LP flare systems. The flare system shall include collecting headers, KO drums, elevated flare stack and HP/LP flare tips.
2.
SCOPE OF WORK The purpose of this procedure is to set guidelines for excavation and cutting with gouging process. This procedure describes the recommended practices of Carbon Arc Gouging (CAG) and cutting, and provides a general description of components used for the process, and process consumables.
3.
DEFINITIONS Project
South Pars Gas Field Development Phase 12, Topsides.
Company
Petro Pars Limited
Contractor
Iranian Offshore Engineering and Construction Company (IOEC) responsible for engineering, procurement, construction of topsides.
Subcontractor
The company selected by the Contractor and approved by Company for performance of the part of the work.
Third Party Agency
Fabrication certifying authority (TPA).
Inspection Agency
Designated Third Party Inspection agency carrying out Inspection.
Inspector
The Company's/Contractor's representative and member(s) of inspection agency appointed for inspection of fabrication works.
Approval
the authorization in writing given by the Company and/or TPA to the Contractor to proceed with the performance of a specific
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 5 of 11
part of the work without releasing in any way the Contractor from any of its obligations or liabilities under the contract or at law: Approve, Approved and Approval shall be construed accordingly.
4.
May
Used to indicate that a provision is optional
Shall
Used to indicate that a provision is mandatory.
Should
Used to indicate that a provision is not mandatory but is recommended as good practice.
REFERENCED STANDARDS AND SPECS.
4.1 Company Specifications Document/ Specification
Rev.
Description
SP12-20-D-23-4-003
Latest
General Technical Specification - Structural Fabrication
SP-12-20-D-04-1-013
Latest
Welding procedure
SP-12-20-D-04-1-022
Latest
Welding repair procedure
Document/ Specification
Rev.
Description
AWS D1.1
2002
Structural Welding Code - Steel
AWS C5.3
2000
Recommended Practice for Air Carbon Arc Gouging and Cutting
4.2 International Standards
5.
PROCEDURE The CAG process requires a welding power source, a source of compressed air, carbon electrode, and cutting torch. Compressed air is introduced to blow away the molten metal. Figure 1 shows the typical arrangement for using this process. CAG is used with DCEP (reverse polarity). The electrode should have a maximum extension of 180 mm from the cutting torch, with the air jet between the electrode and the workpiece. Although there is no minimum extension, care should be taken to prevent damage to the torch. Therefore 38 to 51 mm minimum extension is recommended. Progression should only be in the direction of air flow. The electrode push angle will vary, depending on the operation being performed. The cutter should maintain the correct arc length to allow the air jet to properly remove the molten metal (see Figure 2). Gouging process shall be done by skill person, approved by Company or TPA.
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Doc Title:
Gouging Procedure
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Figure 1 - Typical Arrangement for the Carbon Arc Gouging (CAG)
Figure 2 - How a Standard CAG Torch Works
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Doc Title:
Gouging Procedure
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5.1 Electrodes There are three basic types of electrodes: a.
DC copper coated electrodes. This type is most widely used because of its comparatively long electrode life, stable arc characteristics, and groove uniformity. These electrodes are available in the following diameters: 3, 4, 5, 6, 8, 10, 12, 16 and 19 mm. The copper coating improves electrical conductivity providing more efficient, cooler operation and helps maintain electrode diameter at the point of the arc.
b.
DC uncoated electrodes. This type has limited use. These electrodes are generally used in diameters of less than 10 mm. During cutting these electrodes are consumed more rapidly than the coated electrodes. They are manufactured the same as the coated electrodes without the copper coating.
c.
AC copper coated electrodes. These electrodes are made from a special mixture of carbon and graphite with a suitable binder. Rare-earth materials are incorporated to provide arc stabilization for cutting with an alternating current. These electrodes, coated with a controlled thickness of copper.
5.2 Operating techniques a.
Gouging. Table 1 shows suggested current ranges for various electrode types and sizes. The electrode is gripped, so that a maximum of 180 mm extends from the cutting torch. The air jet should be turned on before striking the arc, and the cutting torch should be held as shown in Figure 3. The torch should always be operated using the forehand technique, i.e., the electrode and air jet pointed in the direction of travel. Under proper operating conditions, the air jet is expected to sweep beneath the electrode end and remove all molten metal. The steadiness of progression controls the smoothness of the resulting cut surface.
Figure 3 - Flat Position Gouging
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Doc Title:
Gouging Procedure
Document No Date Page
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Table 1 - Suggested Current Ranges for Commonly Used Electrode Types and Sizes Electrode Diameter (mm) 3
DCEP Polarity (amperes) 30 – 60
AC Electrode (amperes)
4
90 – 150
5
200 – 250
200 – 250
6
300 – 400
300 – 400
8
350 – 450
325 – 425
10
450 – 600
350 – 450
13
800 – 1000
500 – 600
16
1000 – 1250
19
1250 – 1600
25
1600 – 2200
For gouging in the vertical position, the cutting torch should be held as shown in Figure 4. Gouging should be done in a downhill direction, which permits gravity to assist in removing the molten metal. Gouging in the horizontal position may be done either to the right or to the left, but always with forehand gouging. In gouging to the left, the cutting torch should be held as shown in Figure 5. In gouging to the right, the cutting torch will be reversed to locate the air jet behind the electrode. When gouging in the overhead position, the electrode and torch should be held at an angle that will prevent molten metal from dripping on the cutter's glove, as shown in Figure 6. The depth of the groove produced is controlled by the travel speed. Grooves up to 25 mm deep may be made. Slow travel speeds produce a deep groove. Fast speeds will produce shallow grooves. The width of the groove is determined by the size of the electrode used and is usually about 3 mm wider than the electrode diameter. Wider grooves may be made with an electrode that is oscillated with a circular or weave motion. When gouging, a push angle of 65 degrees from the surface of the workpiece is used for most applications (Figure 7). A steady rest is recommended in gouging to ensure a smoothly gouged surface. It is particularly advantageous for use in the overhead position.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
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Figure 4 - Vertical Position Gouging
Figure 5 - Horizontal Position Gouging
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Gouging Procedure
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Figure 6 - Overhead Position Gouging
65°
Figure 7 - Gouging Electrode push angle
b.
Cutting. Figure 8 shows the electrode in position for cutting. In general, the cutting technique is the same as for gouging, except that the electrode is held at a steeper angle; that is, with a push angle between 10 and 20 degrees. With the electrode in this position, the metal may then be cut by moving the arc up and down through the metal with a sawing motion.
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Doc Title:
Gouging Procedure
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Figure 8 – Cutting with CAG
5.3 Inspection The free carbon particles are rapidly absorbed by the melted base metal. Increased carbon can lead to increased hardness and possible cracking. Since this absorption cannot be avoided, to avoid difficulties with carburized metal it is important that all carburized molten metal be removed from the cut surface. Thus, gouging area shall be cleaned by grinding and brushing. After grinding, these areas shall be inspected visually for recognize removal all carburized metal. Following grinding, the preparation shall be fully inspected visually before the commencement of welding. Where there are visual indications, PT or MPI shall be applied to ensure that the gouging areas are free from defects before welding.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 2 of 11
TABULATION OF REVISED PAGES
PAGE 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34
Revision D0 D1 X X X X X X X X X X X
D2
PAGE
Revision D0 D1
D2
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 3 of 11
Table of Contents
Page
1.0
INTRODUCTION
4
2.0
SCOPE OF WORK
4
3.0
DEFINITIONS
4
4.0
REFERENCED STANDARD AND SPECS
5
5.0
PROCEDURES
5
5.1 5.2 5.3
Electrodes Operating techniques Inspection
7 7 11
Table 1 - Suggested Current Ranges for Commonly Used Electrode Types and Sizes
8
Figure 1 - Typical Arrangement for the Carbon Arc Gouging (CAG)
6
Figure 2 - How a Standard CAG Torch Works
6
Figure 3 - Flat Position Gouging
7
Figure 4 - Vertical Position Gouging
9
Figure 5 - Horizontal Position Gouging
9
Figure 6 - Overhead Position Gouging
10
Figure 7 - Gouging Electrode push angle
10
Figure 8 – Cutting with CAG
11
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
1.
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 4 of 11
INTRODUCTION The offshore development shall consist of three identical wellhead platforms SPD12A, B, C each with 15 slots for field exploration located in approximately 70 m water depth, each linked to a remote flare platform through a two span bridges. Topsides design features shall be according to minimum production facilities concept consisting of fluid gathering, chemical injection, well testing, condensed and saturated water separation and oily water treatment. The platforms shall be designed for drilling through jack-up operations. All the three platforms shall be unmanned and personnel from shore shall perform major operations, whereas routine and emergency operations shall be carried out from nearby offshore complexes built within NIOC South Pars Phase-1 development. Personnel will come on board by boat or by helicopter on temporary basis and as such a shelter to accommodate 6 people on a temporary basis shall be included. Each wellhead platform shall be designed for maximum production capacity of 1200MMSCFD although the planned production shall be 1000 MMSCFD of equivalent well fluid. Each of the wellhead platforms shall have HP/LP flare systems. The flare system shall include collecting headers, KO drums, elevated flare stack and HP/LP flare tips.
2.
SCOPE OF WORK The purpose of this procedure is to set guidelines for excavation and cutting with gouging process. This procedure describes the recommended practices of Carbon Arc Gouging (CAG) and cutting, and provides a general description of components used for the process, and process consumables.
3.
DEFINITIONS Project
South Pars Gas Field Development Phase 12, Topsides.
Company
Petro Pars Limited
Contractor
Iranian Offshore Engineering and Construction Company (IOEC) responsible for engineering, procurement, construction of topsides.
Subcontractor
The company selected by the Contractor and approved by Company for performance of the part of the work.
Third Party Agency
Fabrication certifying authority (TPA).
Inspection Agency
Designated Third Party Inspection agency carrying out Inspection.
Inspector
The Company's/Contractor's representative and member(s) of inspection agency appointed for inspection of fabrication works.
Approval
the authorization in writing given by the Company and/or TPA to the Contractor to proceed with the performance of a specific
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 5 of 11
part of the work without releasing in any way the Contractor from any of its obligations or liabilities under the contract or at law: Approve, Approved and Approval shall be construed accordingly.
4.
May
Used to indicate that a provision is optional
Shall
Used to indicate that a provision is mandatory.
Should
Used to indicate that a provision is not mandatory but is recommended as good practice.
REFERENCED STANDARDS AND SPECS.
4.1 Company Specifications Document/ Specification
Rev.
Description
SP12-20-D-23-4-003
Latest
General Technical Specification - Structural Fabrication
SP-12-20-D-04-1-013
Latest
Welding procedure
SP-12-20-D-04-1-022
Latest
Welding repair procedure
Document/ Specification
Rev.
Description
AWS D1.1
2002
Structural Welding Code - Steel
AWS C5.3
2000
Recommended Practice for Air Carbon Arc Gouging and Cutting
4.2 International Standards
5.
PROCEDURE The CAG process requires a welding power source, a source of compressed air, carbon electrode, and cutting torch. Compressed air is introduced to blow away the molten metal. Figure 1 shows the typical arrangement for using this process. CAG is used with DCEP (reverse polarity). The electrode should have a maximum extension of 180 mm from the cutting torch, with the air jet between the electrode and the workpiece. Although there is no minimum extension, care should be taken to prevent damage to the torch. Therefore 38 to 51 mm minimum extension is recommended. Progression should only be in the direction of air flow. The electrode push angle will vary, depending on the operation being performed. The cutter should maintain the correct arc length to allow the air jet to properly remove the molten metal (see Figure 2). Gouging process shall be done by skill person, approved by Company or TPA.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 6 of 11
Figure 1 - Typical Arrangement for the Carbon Arc Gouging (CAG)
Figure 2 - How a Standard CAG Torch Works
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 7 of 11
5.1 Electrodes There are three basic types of electrodes: a.
DC copper coated electrodes. This type is most widely used because of its comparatively long electrode life, stable arc characteristics, and groove uniformity. These electrodes are available in the following diameters: 3, 4, 5, 6, 8, 10, 12, 16 and 19 mm. The copper coating improves electrical conductivity providing more efficient, cooler operation and helps maintain electrode diameter at the point of the arc.
b.
DC uncoated electrodes. This type has limited use. These electrodes are generally used in diameters of less than 10 mm. During cutting these electrodes are consumed more rapidly than the coated electrodes. They are manufactured the same as the coated electrodes without the copper coating.
c.
AC copper coated electrodes. These electrodes are made from a special mixture of carbon and graphite with a suitable binder. Rare-earth materials are incorporated to provide arc stabilization for cutting with an alternating current. These electrodes, coated with a controlled thickness of copper.
5.2 Operating techniques a.
Gouging. Table 1 shows suggested current ranges for various electrode types and sizes. The electrode is gripped, so that a maximum of 180 mm extends from the cutting torch. The air jet should be turned on before striking the arc, and the cutting torch should be held as shown in Figure 3. The torch should always be operated using the forehand technique, i.e., the electrode and air jet pointed in the direction of travel. Under proper operating conditions, the air jet is expected to sweep beneath the electrode end and remove all molten metal. The steadiness of progression controls the smoothness of the resulting cut surface.
Figure 3 - Flat Position Gouging
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 8 of 11
Table 1 - Suggested Current Ranges for Commonly Used Electrode Types and Sizes Electrode Diameter (mm) 3
DCEP Polarity (amperes) 30 – 60
AC Electrode (amperes)
4
90 – 150
5
200 – 250
200 – 250
6
300 – 400
300 – 400
8
350 – 450
325 – 425
10
450 – 600
350 – 450
13
800 – 1000
500 – 600
16
1000 – 1250
19
1250 – 1600
25
1600 – 2200
For gouging in the vertical position, the cutting torch should be held as shown in Figure 4. Gouging should be done in a downhill direction, which permits gravity to assist in removing the molten metal. Gouging in the horizontal position may be done either to the right or to the left, but always with forehand gouging. In gouging to the left, the cutting torch should be held as shown in Figure 5. In gouging to the right, the cutting torch will be reversed to locate the air jet behind the electrode. When gouging in the overhead position, the electrode and torch should be held at an angle that will prevent molten metal from dripping on the cutter's glove, as shown in Figure 6. The depth of the groove produced is controlled by the travel speed. Grooves up to 25 mm deep may be made. Slow travel speeds produce a deep groove. Fast speeds will produce shallow grooves. The width of the groove is determined by the size of the electrode used and is usually about 3 mm wider than the electrode diameter. Wider grooves may be made with an electrode that is oscillated with a circular or weave motion. When gouging, a push angle of 65 degrees from the surface of the workpiece is used for most applications (Figure 7). A steady rest is recommended in gouging to ensure a smoothly gouged surface. It is particularly advantageous for use in the overhead position.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 9 of 11
Figure 4 - Vertical Position Gouging
Figure 5 - Horizontal Position Gouging
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 10 of 11
Figure 6 - Overhead Position Gouging
65°
Figure 7 - Gouging Electrode push angle
b.
Cutting. Figure 8 shows the electrode in position for cutting. In general, the cutting technique is the same as for gouging, except that the electrode is held at a steeper angle; that is, with a push angle between 10 and 20 degrees. With the electrode in this position, the metal may then be cut by moving the arc up and down through the metal with a sawing motion.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
Doc Title:
Gouging Procedure
Document No Date Page
: SP12-20-D-04-1-021/D1 : 24-Nov-08 : 11 of 11
Figure 8 – Cutting with CAG
5.3 Inspection The free carbon particles are rapidly absorbed by the melted base metal. Increased carbon can lead to increased hardness and possible cracking. Since this absorption cannot be avoided, to avoid difficulties with carburized metal it is important that all carburized molten metal be removed from the cut surface. Thus, gouging area shall be cleaned by grinding and brushing. After grinding, these areas shall be inspected visually for recognize removal all carburized metal. Following grinding, the preparation shall be fully inspected visually before the commencement of welding. Where there are visual indications, PT or MPI shall be applied to ensure that the gouging areas are free from defects before welding.
This document is the property of N.I.O.C. Any unauthorized attempt to reproduce it, in any form, is strictly prohibited
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