Company Profile 
Henan Dongfanglong Machine Manufacture Co., Ltd 
Henan Dongfanglong Machine Manufacture Co., Ltd. was founded in 1999, mainly engaged in oil pipes and pipe fittings, oil special drilling and production tools and oil automation equipments. The company is  named as national integration and standard implementation enterprise, a national science and technology-based small and medium-sized enterprise. With honors of"Henan enterprise technology center", "Henan postdoctoral innovation practice base”, the company hold 35 senior engineers, engineers and technicians, and has successively obtained ISO9001 Quality system certificates,  API 5CT certificate authorized by American Petroleum Institute and BV Quality supplier evaluation certificate issued by company of France. Owing more than 30 independent intellectual property rights, forming an industrial chain integrating design, development, manufacturing, testing and experiment of numerical control automation equipment for petroleum machinery products, which can meet customers' demand for products Full cycle service. 
The company has established the “Dong Fang Yunlong E-commerce Trading Platform" with oil drilling and production equipment and tools as the radiation point, improved the ability of Internet cross-border e-commerce, and completed the transformation of enterprise from internal operation to building industry alliance. It has built an intelligent workshop, expanded the support of intelligent manufacturing for enterprise operation, created a new intelligent manufacturing mode with high efficiency and flexibility, and improved the core competitiveness of the enterprise. And successfully registered production and sales companies in the Netherlands, opening a new starting point for overseas investment and development. 
In the future, Dongfanglong will closely focus on national policy orientation and innovation driven development strategy, formulate sustainable development transformation strategy, keep forging ahead, take creating world famous brand and winning honor for the nation as the goal, work together with people of insight from all walks of life for win-win cooperation, and build up the dream of oil equipment manufacturing.

API SPEC 5CT Oil Well Sub
The oil and gas industry is one of the most important industries in the world, providing a large part of the energy needed by the economy and industry. To extract oil and gas from the ground, a complex apparatus of pipes, fittings and tools is required. One of the key components is the oil casing joint, which is used to connect two spools and maintain the tubing and downhole tools. There are two main types of oil casing joints: oil pipe joints and casing joints. Tubing fittings are used to connect smaller diameter pipes while casing fittings are used to connect larger diameter pipes. Both types of accessories are essential to the proper functioning of oil and gas extraction operations. The thread types used in oil casing joints are non-upset thread (NU), externally upset thread (EU), long round thread (LC), short round thread (SC) and buttress thread (BC); thread type selection Depends on the specific application and requirements of oil and gas extraction operations. The grade of tubing and casing fittings is also an important consideration. Common grades include K55, J55, N80-1, N80Q, L80-1, and P110; the choice depends on the requirements of the specific oil and gas production operation.

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