内衬复合钢管管端封焊到堆焊的改进

为了避免管端封焊引起的刺漏事故，通过采用不同基体及焊接材料、不同坡口形式、不同焊接方法进行焊接试验，并对焊后的管材及焊缝进行硬度测试。测试结果表明，采用不同基体及焊接材料、不同坡口形式、不同焊接方法焊后的硬度值存在很大差异。采用309L Mo材料封焊，无论选用何种坡口形式，均存在硬度超标问题；采用NiCrMo-3材料，无论选用封焊还是堆焊，母材、焊缝和热影响区的硬度都能达到标准要求；堆焊相对于封焊，能够减少焊接缺陷，避免应力集中，适用范围更广且有利于现场施工。建议内衬复合钢管端部处理方式为管端堆焊。

Improvement of the Sealing to Surfacing of Lined Steel Pipe End

In order to avoid the piercing-caused leakage of pipe end sealing, the welding tests are carried out by using different groove types and welding methods for different base metals and welding materials, and the hardness of welded pipe and weld are tested. The test results show that the hardness of base metals and welding materials with different groove forms and different welding methods are very different. Using 309L Mo for sealing, no matter which groove form is chosen, the hardness exceeds the standard; using NiCrMo-3 material, the hardness of base weld and heat affected zone can meet the standard requirements, no matter it is used for sealing or surfacing, the hardness of base matel, weld and heat affected zone can meet the standard requirements, no matter it is used for sealing or surfacing; compared with sealing, surfacing can reduce welding defects, avoid stress concentration, had wider application and be conducive to site construction. It is suggested that the end of lined composite steel pipe should be surfacing.