With an estimated 3800 kilometres of petroleum pipeline in South Africa it is safe to say that the Pipeline Industry is an essential part of the country’s economy. Numerous manufacturing concerns are involved in this industry, supplying both up and down stream products and services to Government and Private entities in the Petro-chemical and Power- generation markets. Maintenance of all pipelines are of utmost importance as any breakdown may cause massive disruptions to various sectors including but not limited to Aviation, Industrial, Hospitality and Medical sectors, not to mention the massive impact that it will have on the already fragile business environment.
Repairs and refurbishing of these pipelines and components are an ongoing process and require specialist products to ensure the job is done correctly, thereby shortening the repair time and ensuring better longevity of the pipelines. A critical area on a pipeline is the joint. When two parts are joined together, it is essential to create a solid joint. In most cases joints are welded together and it is essential that the weld area is without flaws, cracks or defects. In preparation for the welding process a piece of material is bevelled in order to provide better access to the root or inside edge of the material, this bevel area should be finished off with a product that will effectively prepare the surface for welding, while not contaminating it. Some welding procedures will require finishing the bevel with a 120-grit flap disc to best prepare the surface – Grinding Techniques Superflex Flap Discs are perfectly suited to this application and is available in both a flat type 27 and angled type 29 configuration. Once this is done,the welding procedure can commence.
A root run is laid down in the root channel, which will need to be back ground to remove any potential defects like porosity and or poor fusion of the materials. Back grinding is therefore the process of removing the outer part of the weld to ensure that any impurities that floats to the top of the weld is removed before a final weld or cap is added on to “seal” the weld-joint. Grinding Techniques manufactures various products specifically for this purpose, depending on the thickness of the material and size of the root channel a Superflex 230×4.1×22.23mm AS30T disc is ideal for root channels of approximately 3mm, and a Superflex 230×5.2×22.23mm AS30T disc will suit the requirement for channels wider than 3mm.
In the past, most operators would use a 230mm cutting disc for this purpose – the disc would be placed in the section and then twisted to clean and grind the weld out. This is a very dangerous practice and this should be avoided at all cost as cutting discs are not designed to handle this type of side load pressures that they will be placed under. The Superflex back grinding products’ construction allows for much safer work to be carried out. After completing the welds, the pipe or section will be x-ray inspected for flaws or defects. If the above process is followed correctly, the weld can be passed. If a defect is identified on x-ray, a thinner disc may be required to cut or grind out the material in order to lay down another weld. One such disc is the range of Dual Purpose Cutting and Grinding discs from Grinding Techniques – available in 115×2.2×22.23mm, 125×2.2×22.23mm and 150×3.0x22.23mm, these discs are ideally suited to both cutting and grinding applications. The emphasis here being on the fact that these discs are constructed to be safe when cutting and grinding with the same product. Conventional
cutting discs can and probably will break if used in this manner.
The final area that needs to be checked on the joint will be the area between the top of the bevel and the filler cap of the weld. If the weld forms a sharp corner, this may be rejected as it might cause a failure in the weld. The Superflex 115×2.2×22.23 A36S CG (Cut and Grind) is ideal for blending of these areas to ensure a smoother finish and a pass on the inspection. Conventional thickness grinding discs tend to remove too much material, making the thinner disc ideal for the finer work required. The thinner disc also produces less heat, which is essential for heat sensitive materials that may crack.
One often over looked area of any abrasives is the safety factor. When the incorrect product is used for any application, the potential for disaster is enormous. Grinding Techniques designs, manufactures and tests all products to international standards to ensure that the operator is kept safe, when products are utilised for their intended purpose. The capability also exists for products to be designed for a specific application where no such product currently exists. The products mentioned above all have that focus in mind – create a product that will get the job done quickly, effectively and with the maximum amount of safety possible.