Feed to the new Ecocarburantes de Repsol Cartagena plant
API 5L-X52 steel pipe,
Diameter: 12 in (219 mm)
Pipe wall thickness: 18 mm.
Operating pressure: 59 bar
Gas temperature: 12-15ºC
Welding of a Way-Tee in a natural gas pipe line.
During the project, the pipe is at full gas load, pressure and flow to feed the Repsol Cartagena refinery.
This is a dangerous operation, but essential for pipe repairs or for adding another gas line from the main pipe.
The indispensable step prior to carrying out the work is the qualification of the welding procedure, and of course, to have perfectly qualified welders to execute the job. Welds are made on specimens with characteristics similar to those of the work to be carried out and all the properties to be met are tested. If the results are positive, the Welding Procedure is qualified (WPQR).
Before starting to weld and during the whole process, the area to be welded must be kept at a temperature of 100-120ºC, to ensure that the pipe wall affected by the welding, remains tough and thus avoid cracking in that area. Temperature will also influence that the properties of the pipe remain the same and so, its programmed service life is not affected. This can be ensured if the essential parameters of the Welding Procedure (WPS) are respected.
Heating is difficult because the gas flows at a high flow rate through the tube at a temperature of about 15ºC, which continuously cools the area to be kept hot for welding.
The modern induction heating equipment that Solysol has incorporated is of essential use in this highly responsible work.
| The optimum pre-heating and interpass temperature was previously established by qualification of the welding procedure. Several tests were carried out to study the variation between the welding temperature and the toughness of the Weld Heat Affected Zone.
It was therefore essential to achieve and maintain a temperature of 100 to 120ºC during the entire welding operation. This was made possible thanks to the well studied induction heating process developed by SOLYSOL during the execution of the project. |
|
After preparing the ditch and removing as far as possible the pipes adjacent to the pipe on which the “T” or Way-T is to be welded, the measurements of the fitting are taken to begin the preparation of the pipe to accommodate this fitting.
Induction heating cables are placed on both sides of each of the areas where a weld overlay is to be welded on which the circumferential fillet welds joining the Way-T to the pipe will be made.
The induction heating equipment allows the desired minimum preheating temperature of 100ºC to be reached in less than 30 minutes, and once this temperature is reached, it remains stable throughout the process.
This provides great peace of mind that the entire weld and its adjacent zone on the pipe will have the required toughness properties so as not to affect its service life.
The performance of the necessary tests and the control of the welding execution is carried out by a Welding Engineer and a SCWI, Senior Certified Welding Inspector by the American Welding Society (AWS). All work is scheduled, supervised and approved by a SCWI (Senior Certified Welding Inspector),Angela Lazaro.
The welder of proven experience, qualification and certification, is Fernando Sanchez Deza, who also supervises other welders who are required to carry out more extensive work.
The staff dedicated to repairs of great responsibility, as in this work, has a great experience, qualification and certification. In addition, their continuous training and study and their passion for the work they do are an excellent guarantee for customers who have this type of needs.
 |
 |
3.1 Preparation and control of all required equipment and material
3.2 PREHEATING of the area to be welded
3.3. Welding the circumferential Buttering at both sides of the seat of the cylinder
3.4. Preparation of shingles or halves for longitudinal joining
3.5. Longitudinal welds of the two halves of the Way-Tee
3.6. Fillet welds the circumferential welds on both sides of the Way-Tee to the pipe.
3.1 Preparation and control of all required equipment and material
3.2 PREHEATING of the area to be welded
Solysol supplied welding, induction heating and auxiliary equipment for the project:
A small but very powerful welding equipment: the ESAB RENEGADEThe RENEGADE, which was able to withstand hours of work, non-stop welding of high-quality basic electrodes, vacuum-packed and kept in a portable quiver once the packages had been opened, OK 48.00up to 4 mm in diameter.
Control of the preheating and interpass temperature is essential, throughout the whole perimeter.
Heating with SOLYSOL induction equipment allowed to achieve a constant temperature of 100-120ºC during the whole welding process.
Continuous control of the preheating temperature and maintenance in the entire perimeter and longitudinal areas of the areas adjacent to the weld.
Hardness control in these affected areas, to ensure the toughness of the welded areas.
One of the most important challenges was the maintenance of this temperature throughout the entire welding process, in each one of the repairs: During buttering, longitudinal groove welds and circumferential fillet welds. The gas circulating through the tube at a temperature of 12-15ºC, at a pressure of 59 bar and high flow, acting as an instant coolant for any heating we try to apply to the outside of the tube.
The development of the heating procedure was one of the major achievements during this in-service pipeline branching project. This guarantees the tenacity of both the welded fitting and the original tube on which it sits, and therefore the integrity of the repair to offer full service warranty, as original.
3.3. Welding the circumferential Buttering at both sides of the seat of the cylinder
Performing “buttering” or weld overlay on both sides of the Way-Tee to provide adequate support for the fillet weld at its circumferential joint with the original pipe.
The welder must adjust his posture so that the weld is perfect, pass by pass, around the entire circumference of the pipe.
Cleanliness between each of the passes is essential to avoid leaving defects, as well as control of the arc at all times, which means enormous concentration on the work even in uncomfortable postures.
After surfacing welding, non-destructive testing is performed to ensure that there are no defects: Visual Examination, Liquid Penetrant, Ultrasonic and Dimensional Control.
3.4. Preparation of shingles or halves for longitudinal welds
Steel strips of the same quality as the tube are inserted on both sides of the base half of the Way-Tee.
This ensures that the pipe will not be affected during the longitudinal welds that will be made on both sides to close the graft.
The Way-Tee is placed in the tube, just between the two circumferential claddings previously made.
Induction heating cables that will ensure the desired preheating temperature throughout the process of closing the fitting are placed in the longitudinal and fillet welds around the perimeter of the pipe.
3.5. Longitudinal welds of the two halves of the Way-Tee
3.6. Fillet welds the circumferential welds on both sides of the Way-Tee to the pipe.
Making the longitudinal welds joining the two tiles to close the fitting around the pipe.
Subsequent execution of circumferential fillet welds between cladded areas and Way-Tee
Repair executed in record time, once the minimum safety conditions and guarantee of the integrity of the pipeline and personnel at the pipe line area and in the execution of repairs were established.
Maintenance of pipeline service conditions throughout the entire process.
