ASTM A270 seamless stainless steel pipe | How to control quality？

ASTM A270 seamless stainless steel pipe is widely used in high-pressure steel pipes and low-temperature corrosion resistant pipeline systems. Mechanical performance, process performance, and corrosion resistance are three important indicators to measure the quality of steel pipes, and also an important guarantee for ensuring safe navigation of ships. In practical ship applications, stainless steel chemical ships discovered leakage in the deck cargo pipeline system after their first voyage, and pressure tests revealed more than 10 holes leaking. During the manufacturing process of ethylene ship cargo tanks, many surface quality issues were found on the inner surface of the tank pipes, including internal wall pitting and surface cracks. So, how to fundamentally solve these problems? The answer is simple, we should strictly control the quality of raw materials and intermediate products. The specific situation is as follows:

1. Control the quality of raw materials

The raw materials used for producing ASTM A270 seamless stainless steel pipes are mainly continuous casting round tube billets. Rolling (forging) round steel is the first step to ensure the quality of the steel billets, mainly including steelmaking level, pouring and cooling processes, and forming quality. Firstly, it is necessary to improve the level of steelmaking, reduce harmful and gaseous elements and gases (nitrogen, hydrogen, oxygen), improve the uniformity and purity of components, reduce non-metallic inclusions, and change their distribution.

2. Ensure the accuracy and uniformity of hot furnace temperature control

The hot furnaces used in the manufacturing of ASTM A270 seamless stainless steel pipe include billet heating furnaces and steel pipe heat treatment furnaces. The accuracy and uniformity of temperature control are two important indicators for judging the quality of heating equipment, and are also important guarantees for the heating process. Therefore, manufacturers should strictly follow the regulations on the usage and calibration cycles of thermocouples, and test the uniformity of furnace temperature.

3. Optimize the inspection process and equipment

Intermediate product inspection is the key to controlling the quality of finished pipelines, especially the surface quality of the inner wall, which must be paid attention to from the source. Firstly, we need to establish a reasonable organization with effective inspection and handling procedures to ensure that existing problems can be identified and effectively addressed.
In addition, it is necessary to establish an effective defect feedback system, analyze and count defects in a timely manner, such as defect category, generation stage, and frequency. Clear defects according to unified process guidance, and analyze the causes of defects in a timely manner.