First, the method of drilling seamless steel pipes
1. Use a special punching machine to drill the inner diameter of the steel pipe to the required specifications. Before drilling, the pipe should be inspected for cracks, folds, severe corrosion, and other defects. If there are any defects mentioned above, they must be removed before drilling.
2. On the punching machine, select the corresponding drill bit according to the steel pipe of the required specifications (usually a diamond-beaded electric drill bit with a diameter of 32mm or 40mm), then adjust the appropriate rotation speed and feed amount before starting drilling.
3. When the wall thickness of the steel pipe is less than 4mm, a small-diameter diamond bead-type electric drill bit can be used; if the wall thickness is greater than 4mm, a large-diameter diamond bead-type electric drill bit (such as Φ50) should be used.
4. During the drilling process, you should always pay attention to the situation at the bottom of the hole and adjust the speed and feed amount in time to prevent wire breakage.
5. When the steel pipe passes through the metal casing, the hollowing operation is completed.
Second, precautions for drilling holes in seamless steel pipes
1. It is strictly forbidden to use the electric hammer impact method to process and perforate seamless steel pipes with serious cracks; otherwise, the strength of the steel pipe will be destroyed and the service life will be affected. If defects such as cracks, heavy skin, or scarring are found on the surface of the steel, or if there are deep local scratches, electric hammer processing should also be avoided. (This method is not suitable for seamless steel pipes made of cold-drawn hot-rolled steel plates)
2. For seamless stainless steel pipes used for gas transportation, hydrostatic tests are usually used to check whether their pressure resistance meets the requirements (according to the standard GB/T12771-2000: the hydrostatic test pressure is 1.5 times the working pressure, and the pressure holding time is not less than 5 seconds).
3. For seamless stainless steel pipes used in hydraulic props, hydraulic tests are usually used to check whether their pressure resistance meets the requirements (according to the standard GB/T12771-2000: the hydraulic test pressure is 1.15 times the nominal pressure; the pressure stabilization time is quite long in 10 seconds).
4. Seamless stainless steel pipes for boilers that bear fluid loads and have high operating temperatures are often used as liquid delivery pipes and require leak detection. (According to the standard GB/T13396-92: the leakage detection pressure is twice the nominal pressure; the time is 30 minutes.)
5. Leak detection is required for high-pressure oil pipes used in high-pressure vessels, which are often used as gas transmission pipelines. (According to the standard GB/T14383-93: the leakage detection pressure is 2.5 times the nominal pressure; the time is 1 hour.)
6. Since cracks are prone to occur at welded joints, the effective cross-sectional area of the weld is reduced, causing increased leakage and even catastrophic accidents. Therefore, welding quality must be strictly controlled.
Post time: Mar-27-2024