Metal pipeline construction points for attention in winter, the biggest characteristic of winter construction I think is that the temperature is relatively low, in the welding operation must pay attention to the temperature, the need to determine the temperature of the welding position before welding, in the case of lower than the process requirements of the temperature, the base metal must be preheated before welding. Attention should be paid to the thermal insulation problem after welding in winter. Attention should be paid to keep the materials dry in rain and snow. Measures should be taken during the welding construction in winter. If the temperature is above -5 degrees Celsius, do some conventional drying and insulation. If the temperature is too low or the board is too thick, we need to preheat and pay attention to the insulation between layers.
Winter construction main technical measures
1. Pipe welding should be preheated in strict accordance with the requirements, and the pipe should be put into the closed workshop for heating in advance.
2. when the ambient temperature is below 5℃, it is not suitable for hydraulic test; The water of the pipeline that has been tested by hydraulic pressure should be drained out of the pipe in time and the pipe mouth should be temporarily blocked.
3. should try to avoid the pipeline pressure test in winter, if it must be in winter pressure test, to minimize the water filled pipeline exposure to the natural environment time, in line with the requirements of the specification under the premise, the test time should be as short as possible, after the test, to drain the water in the pipeline in time and maximize the blow dry.
4.The amount of prefabrication should be increased as much as possible to reduce the welding workload on site.
5. The wind speed during welding shall not exceed the following provisions; otherwise, windproof measures shall be taken:
A manual arc welding is 8m/s;
B hydrogen arc welding, carbon dioxide gas welding 2m/s
6.The relative humidity of the environment within 1m welding arc shall not be greater than 90%.
7. the welding environment temperature should be able to ensure that the welding parts required sufficient temperature and welder skills will not be affected.
8. Welding process requirements:
A When the ambient temperature is below 0℃, welding joints without preheating requirements, except austenitic stainless steel, should be preheated to more than 15℃ within 100mm of the initial welding site.