1. Structure: it is a normal api standard deposition with tungsten alloy coatings on the ir inner and outer walls. 2. The performance indicators: Basic performance: meet api standards. Corrosion properties: resistance to corrosion of H2s and Co2 with high temperature, salt water, alkali and weak acid corrosion, meeting the corrosion resistance requirements of standard nace 0177. Wear resistance: good wear resistance, equivalent to hard chromium layer. Adhesion of tungsten alloy layer and substrate: tested according to gb / t5270-2005, the tungsten alloy layers dont crack of peel off. Appearance: uniformly bright, silvery white Tungsten alloy layer thickness: 40-60 3. Performance testing Wear and corrosion test: having passed a variety of the wear and corrosion resistance tests carried out by an cnpc tubular goods research institute, xian maurer petroleum engineering laboratory, and quality supervision and inspection center of surface covering layer products for machinery industry. Standard shipping packaging, as required