The quality of pressure vessels mainly depends on the control of all processes in the whole process of production, especially the key processes. Long-term production practice has proved that this is the most reliable quality control method, is also the most economic quality assurance measures. If we only emphasize the final overall quality inspection and neglect the control of the whole process of production, it is likely to cause significant economic losses. Therefore, we must pay attention to each link in the actual production, and strictly in accordance with the relevant standards and specifications of the implementation of manufacturing, only in this way can ensure the final quality of products.

Process control of pressure vessels

In the process of pressure vessel manufacturing, the first thing to do is to prepare a complete set of process documents and inspection plans for each pressure vessel. These documents have the role of guiding production, ensuring quality and improving efficiency. Of course, the preparation of these documents is often not enough, the key is in the construction process, to strictly implement these documents, so that in the process of product manufacturing, the last process does not check, does not confirm does not sign, the product or parts shall not enter the next process. This involves the key points that need to be controlled in the process of pressure vessel manufacturing.

Cutting and layout drawings of pressure vessels

Cutting drawing and layout drawing is a key point to control, head and cylinder cutting, cylinder group and even line opening according to cutting drawing and layout drawing. Before the head and cylinder are blanked, the technician shall draw the blanking cutting drawing according to the sheet size and design drawing provided, and draw the layout drawing according to the opening orientation and size of the blanking drawing and design drawing. For shop opening position and open hole diameter are to be carried out according to the technical personnel the typesetting figure line hole, so in the process, technical personnel should carefully to verify the layout diagram drawn, especially for an opening in a layout diagram location and size in the process of reviewing to avoid to take over the hole size and position to make wrong and cause irreparable damage.

Welding operation instruction of pressure vessels

The manufacturing quality of pressure vessel is directly related to its safety, reliability and service life in operation. Welding quality control in manufacturing process is the key to ensure its quality. How to ensure the welding quality and welding quality to control better, this request according to the welding procedure qualification and combines the actual conditions of factory set reasonable welding working instruction, when making wi, welding technical staff when making work instructions cannot be divorced from reality, in this process, to combine with welding operators on, adopts what kind of welding method, What type of groove to open, how much groove Angle to open, and how much blunt edge to leave will require the welding technician to work with the welding operator to develop a work instruction that conforms to process evaluation, ensures quality, and is easy for the welder to operate.

Technical clarificaiton of pressure vessels

How to better transform the design of the drawings into entities, less detources, avoid errors in the manufacturing process, resulting in waste, which requires technical personnel according to the drawings found in the process of joint review of the manufacturing difficulties, technical requirements and manufacturing process need to pay special attention to the place for technical disclosure. The requirements of the construction drawings and standards and specifications should be timely, accurately and clearly communicated to the operators, so that they can carry out construction according to the requirements of the drawings, standards and specifications, so as to produce products that meet the requirements and meet the quality.

Stop yourself of pressure vessels

For pressure vessel manufacturing, what stops do we have and how do we better control these stops? Including head and simplified blanking, line lofting, makeup welding, weld inspection, the school circular tube section, group of cylinder, cylinder hole, to take over the group of the welding, etc., to pressure vessel manufacturing don't make a mistake, have to strictly control the manufacturing process of stop yourself, do stop yourself do not check, do not confirm, do not sign, products or components must not enter the next process. For example, one part of the process is: Take over, manhole tube section, group of forgings and flange for precast welding, in this process requires that stop check check, do strictly according to the figure construction, monitored according to the drawings, to verify the form and the specifications of the flange, sealing surface form, the pressure levels, forging and the flange standard, whether it is consistent with the drawings, in the case of make sure below can be set to and welding, Avoid the rework caused by the construction not according to the drawing. At the same time in this link should also focus on the supervision and control of the use of welding materials, to avoid the use of wrong welding materials because of different materials.

Connection of pipe and housing of pressure vessels

The connection between nozzle and shell is difficult in welding, which is mainly determined by the diversity of connection forms between nozzle and shell, the complexity of force, and the difficult operation of groove processing and assembly quality. The connection between the pipe and the shell is divided into flush type, extension type and placement type. Construction drawings to take over and shell connection request, and not only one kind of form on the one container, how can we ensure not wrong to take over the connection form, which requires the first pressure container manufacturing process, in accordance with the requirements of construction drawings to take over the connection form to make the welding working instruction, and the plumber and welder technical disclosure, When taking over for group pairing, the plumber shall make the groove and group matching according to the connection form of the drawing, and the welder shall carry out the welding work strictly according to the welding type required by the drawing. Take over and casing connection stress is relatively complex, took over the fellowship with vessel's corner area structural discontinuity, easy cause high levels of stress concentration, and the possible existence of residual stress, led the region stress level is very high, often become the container stress concentration area, the most severe plastic is usually lower than the parent metal and weld metal, The weld root and heat affected zone are easy to be the origin of cracks under fatigue load. Therefore, in this process, it is necessary to strictly control, do not allow the strong group, the weld to achieve smooth transition, to avoid the appearance of fusion, penetration, edge bite and other defects. The quality of groove processing and assembly is difficult to operate and control. 

From the welder's construction operation, this kind of weld is the most difficult to control the manufacturing process of all welds on the container, and it is also the most prone to problems. This is because the saddle opening on the shell still adopts a large number of manual opening methods such as gas cutting and air gouging, which is not easy to ensure the groove Angle and blunt edge size. The oxide skin on the groove surface is difficult to remove, and the operating position of the welding pipe is often unfavorable for the welder to control the molding, so it is easy to produce cracks, incomplete welding, fusion, slag and other defects. At the same time, due to the particularity of the structure, RT and UT detection is difficult to operate and there is no clear provision on the connection between the nozzle and the container on the drawing, which reduces the welder's responsibility and makes the weld quality difficult to be guaranteed. So in this process, the operator should increase the groove processing and assembly quality control, improve the accuracy of groove size, groove cleanliness. At the same time, the nozzle height and flange surface inclination should be controlled strictly according to the requirements on the drawing to ensure that these parameters are within the range of the standard requirements. After the completion of the group, the technical quality inspection personnel can confirm the correctness before welding, so as to effectively avoid mistakes, unnecessary rework and waste.