Below is a precise mechanical method statement that describes in detail the removal of existing tubes and installation of new tubes for the Heat Exchangers. Procedure also outlines the method for replacement of existing tubes for Heat Exchanger.
This procedure is one component of a complete replacement of tube work program. This and other procedures will be used, as needed, to provide assurance that replacement of heat exchanger tubes activities are being conducted as required by the specification and manufacturer procedures. It is not expected that completion of the entire procedure will be accomplished during any one inspection and /or every time the inspection procedure is used. It is a continuing activity until all tubes are replaced.
The procedure provides guidance for assessing the activities for replacement of tubes. This guidance is based on the requirements set forth in the project requirements, safety requirements and project quality assurance program.
This document provides guidance in implementing an effective program for replacement of Titanium tubes for the Heat Exchanger. This includes the following:
(1) Implementing commitments regarding the quality of the work.
(2) Managing and providing oversight to ensure installation and related quality control has been adequately addressed by specifications, drawings, and procedures.
(3) Managing and providing supervision and control to assure quality of work and closely implement/monitor schedule.
(4) Recording installation and test activities.
(5) HSE at the time of work.
The project manager has overall responsibility for the coordination and implementations of the cutting and welding activity, including manpower and plant utilization, engineering support, material scheduling and cost control. Project mechanical engineer will also be responsible for the replacement of tubes for the Heat Exchanger.
Tools & Equipment
Below is list of tools and materials.
Tubes: Titanium tubes
Lifting and Rigging Equipment: As per requirement
Scaffolding: As per Requirement.
Other small hand tools and tackles: as per requirement.
Health, Safety and Environment HSE Requirements
Notify all concerned in site for the date of material delivery.
Ensure all workers involved in the operation put on PPE all times.
Brief individual worker the roles and responsibilities of each.
Coordinate with concern department for tubes hoisting area.
Ensure designated area is cleared of obstruction.
Ensure that safe work procedure for replacement of tube operation is observed.
Ensure proper method with the correct equipment are used.
Ensure the pipes/tubes are firmly placed on the designated location before releasing the hoisting hook.
During Replacement of Tubes:
Ensure workers are distributed to each designated place.
Ensure workers at all times to be in proper gear where required.
Ensure all workers assigned are involved in its particular task.
Brief individual worker the roles and responsibilities before start work.
Ensure the pipe/tube lengths to suite site routes into designated work area.
Ensure all tools to be used have been inspected and tagged by safety department.
Ensure work areas are clearly marked to restrict access to authorized personnel only.
Ensure that equipment’s to be used are properly tagged and checked.
Maintain cleanliness and orderly stocking of material and tools.
Pick up and dispose wastes and other debris prior to leaving site area.
Remove safety yellow tape or other warning devices that were used to control access to the work area.
Store tools, equipment and unused materials properly at the end of the workday.
Safety Inspections: It shall be responsibility of the supervisor to routinely inspect the physical areas under their control in pipe welding works.
The following steps will be carried out for replacement of Tubes.
After isolation of the plant, remove end covers on either side of the Heat Exchanger.
Remove the plugs by drilling or tapping method to avoid damaging the tubes.
Cut the tube from one end by using tube cutter tools.
Pull the tube using hydraulic stub puller without damaging the tube sheet.
Place the old tubes in a safe area on the work platform.
Pull all the balance tubes from the tube sheet using above method.
Clean expansion grooves in the tube sheet using cleaning brush or by air to remove debris or deposit material.
Check the diameter of tube sheet bore by using dial caliber.
Clan the baffle holes by using power brush.
Inspection of the tube sheet bore by approved inspection method before inserting new tubes.
Prior to inserting the new tubes, inspection must be approved.
Insert new tubes and expand as per the specified values on both ends as per the calculation method.
After the expansion tubes are measured and checked using dial bore gauge, record the values.
Tubes ends shall be protrude from tubes plates of 3 mm.
Tube ends shall be checked after expanding to make sure there is no damage.
Inside surface of tubes ends in the expanded area shall be free of defects such as crack or clear overlaps.
Prepare the leak test by water for the Heat Exchanger.
Attend the leak tubes by rolling or replacement after testing until exchanger is approved by the client.
Inspection and Recording Requirements
The engineer should verify that the supervisor/foreman with construction responsibilities for the replacement of tubes works is familiar with the method statement and is issued with copies of the inspection checklists and test plans.
The supervisor should verify that the personnel have sufficient knowledge of the procedure requirement. The supervisor should review any training and qualification records for those individuals who shall do the task to determine whether they are skilled enough to follow the procedure before the actual work is carried out.
Engineer should satisfy procedures provided by QA/QC inspections to ensure the replacement of tubes works meet specified engineering requirements and drawings.
As part of the assessment, the QC inspection procedures must ensure quantitative or qualitative acceptance criteria for determining the prescribed activities have been accomplished satisfactorily.
The QC inspection personnel, in coordination with site supervisor, should verify that the quality of the works and related testing activities are within the project design specifications requirements.
Supervisor should verify that the replacement of heat exchanger tubes works is accomplished in accordance with the specifications and the manufacturer’s procedures.
The supervisor should verify any testing and confirm that the information meets the project requirements.