1. PURPOSE
2. SCOPE
3. REFERENCE
4. DEFINITIONS
5. RESPONSIBILITY
6. EQUIPMENT
7. METHOD / PROCEDURES
8. QUALITY CONTROL
9. SAFETY PRECAUTION
10. ATTACHMENT.
Flange facing refers to the process of machining the mating surfaces of flanges to ensure they are flat and smooth, allowing them to form a tight seal when bolted together. It’s essential for preventing leaks in piping systems.
1. PURPOSE
This Procedure and method statement shall provide minimum guidelines for flange facing at storage yard / or work site during construction for plants and refinery projects.
2. SCOPE
This method statement covers the minimum requirement for flange facing as required in project specification and instruction from vendor/manufacturer for plants and refinery projects.
3. REFERENCE DOCUMENT
1. SAES-L-350 Construction of Plant Piping.
2. ASME B16.47 Large Diameter Steel flanges.
3. ASME B16.5 Pipe Flanges and Flanged fittings.
4. ASME B31.1 Power Piping.
5. ASME B31.2 Process Piping.
6. ANSI B46.1 Surface Texture (Surface Roughness, Waviness, And Lay).
7. Vender Procedure : Flange Facing Procedure (MIRAGE MACHINES)
4. DEFINITIONS
4.1 Dead Mans Handle
Air operated pendant/remote control, which controls the machine tool and acts as an emergency stop when released.
4.2 CLA
Centre Line Average (micro inches)
4.3 RA
Roughness Average (micro meters)
4.4 Face Turning Comparison Block
Machined scale consisting of roughness value specimens in metric and imperial to standards BS 2634, ISO 2632 and ANSI B46.1.
4.5 Internal Mount Machine Tool
Portable machine tool, which locates and is mechanically secured in the internal bore of the flange/pipe.
4.6 External Mount Machine Tool
Portable machine tool, which locates and is mechanically secured on the external diameter of the flange/pipe.
5. RESPONSIBILITY
- Construction Manager shall implement all HSE requirements for the job, shall study, analyze and schedule all construction activities with his department to include manpower and equipment line up as well as other possible resources required for the successful implementation of the construction work activities. He shall study all aspects of work procedure as per Technical Scope of Work.
- QC Inspector shall be responsible in monitoring and inspection of the work and ensure that the work is performed in accordance with Technical Scope of Work and Standards.
- QC Manager shall be responsible for the verification of this procedure through audits and surveillances.
6. Equipment Used in Flange Facing
6.1. The basic equipment will include but not limited to :
- Mirage MM250i.
- MM860i.
- MM1150i.
- MM1830i & MM2000i Flange Facing Machines.
7. Flange Facing Procedure.
7.1 Before facing the flange, the Technician will ensure the following:
- All guards are in place before machine is started.
- The air hoses are correctly fitted to both the drives and the supply and any couplings Are secure.
- The machine is clear of obstructions to run free.
- There are no unauthorized personnel in the vicinity and, if necessary, the area has been cordoned off to prevent unauthorized access.
- All protective equipment is being worn.
- Test the operation of the Dead Man’s Handle.
7.2 The following will be adhered to during the facing:
- Ensure guards are in place.
- The tool will be fed at a rate, which gives the required service finish as specified.
- The cut is watched at all times to ensure it is not fouling up the flange face.
- Swarf is removed as necessary after stopping the machine and must only be removed using a suitable tool such as Long Nose or Nail Pliers.
- The flange surface finish will be inspected using a surface finish comparator.
- If the finish is not satisfactory, the flange will be re-faced. (Raised face thickness, outer diameter and respective tolerances shall be as per Para 7.4.3 & 7.4.4)
7.3 The machinist will ensure that the following is adhered to:
- When working at height ensure Scaffold tag is in place and that the scaffold has been inspected.
- When lifting the machine on to the application no surrounding equipment is damaged or personnel endangered.
- If lifting equipment is used, ensure that all site regulations are obeyed and equipment used is capable of the lift and the operator is trained to do so.
- The machine is fitted to the application square and solid in the correct position. This should be checked by the use of measuring equipment.
- Air hoses to be connected to the nearest air supply avoiding fouling walkways and access. (Note. Air hoses should have whip checks and pins fitted at all joints.)
- Air hoses to be connected using whip checks and pins to drive motor(s) ensuring they will not entangle with plant and/or equipment when the machine is running.
- A suitable cutting tool is used to meet the required finish/profile.
- A Dead Man’s Handle is fitted, tested and used in accordance with current procedure.
- There are no unauthorized personnel in the vicinity and the area has been barriered off to prevent access.
- Swarf is removed as necessary after stopping the machine and must only be removed using a suitable tool such as Long Nose or Nail Pliers.
- Good Housekeeping practices are used at all times, and the job site is left in a clean and tidy condition. All loose swarf should be collected and removed using a suitable tool as above or supplied magnet.
7.4 Condition of Joint Face
7.4.1 Raised Face
Raised face flanges shall be free from smooth depression, dents, rust, weld spatter, pitting and scratches. The joint face must also have a surface finish between “CLA125μ to CLA250μ” which can by checked using a Face Turning Comparison Block. When “hydrogen service” is specified in material description, surface finish shall have maximum “CLA125μ” per ASME B46.1
7.4.2 Ring Joint
Ring joint grooves should be checked for smooth depression, out of roundness or visible scratches, which appear within the groove. The sealing faces of the groove must have a surface finish of CLA16μ” to CLA63μ” which can be checked using a Face Turning Comparison Block & the sidewall angles must be 23°.
7.4.3 Raised Face Thickness and Outer Diameter.
Under thickness of Raised face due to refinishing shall be acceptable, provided Raised face height reduction is not more than 0.8mm (0.031in). If reduction in Raised face height is more than 0.8mm, flange shall be machined to achieve required Raised face height. However in such case JGC Engineering shall be consulted for review and confirmation prior to flange refinishing. Outside diameter of Raised face shall be as per Table-4 of ASME B16.5 and Table-31 to Table-35 of ASME B.16.47.
7.4.4 Tolerance.
Dimensional tolerance for Flange and Raised face shall be as per Para.7 of ASME B16.5 and B16.47.
8. QUALITY CONTROL
- Quality Control (QC) inspector shall coordinate with the other inspectors to conduct inspection as required.
- Quality Control (QC) inspection shall check whether or not; surface finish is satisfied.
9. SAFETY PRECAUTION
- Obtain the approval of the work permit as required
- Tools and equipment should be made operational and available for use.
- Sufficient number of fire extinguishers shall be provided to prevent materials and equipment from fire. All warehouse and preservation crew personnel shall be trained in the use of portable fire extinguishers.
- Provide Sufficient warning signs and barricade as required in the area and only assigned and authorized workers will be allowed in the area.
- Good housekeeping shall be maintained around the area. The site of all materials and equipment shall be kept in a clean and tidy manner.
- Approved hearing protection must be worn at all time when machining is running.
- Operation by one person is recommended, however under exceptional circumstances this may not be possible. When two man operation is unavoidable a specific risk assessment must be undertaken by those involved with the task to ensure all additional risks caused by two-man operation have been identified and addressed to ensure the safety of those undertaking the task.
- Use a Dead Man’s Handle at all times.
- Operator must read and understand all operating instructions before using all equipment.
- Do not strike or modify any equipment.
- Never wear loose items of apparel when using rotating machine tools.
- Always tie long hair back prior to using rotating machine tools.
- Ensure that know how to STOP the machine an emergency.
10. ATTACHMENT
10.1. Job Safety Analysis.