CN-122022535-A - Safety evaluation and inspection method for stainless steel forging connection pipe of in-service pressure vessel

CN122022535ACN 122022535 ACN122022535 ACN 122022535ACN-122022535-A

Abstract

The invention belongs to the technical field of special equipment inspection and detection, and relates to a safety evaluation and inspection method for stainless steel forging connection pipes of in-service pressure vessels. The evaluation method comprises the steps of setting a plurality of safety evaluation indexes of the stainless steel forging connection pipes of the in-service pressure container, setting the duty ratio weight and interval coefficient of each safety evaluation index, calculating the actual duty ratio of each safety evaluation index according to the environment used by the stainless steel forging connection pipes of the pressure container, wherein the actual duty ratio is calculated in a mode that the duty ratio weight of the same safety evaluation index is multiplied by the interval coefficient, and judging that the stainless steel forging connection pipes of the in-service pressure container belong to high-risk connection pipes when the sum of the actual duty ratios of the safety evaluation indexes is more than 60%, so that the safety evaluation is completed. The detection method comprises the steps of carrying out nondestructive detection on the high-risk connecting pipe, carrying out on-site metallographic film coating detection on the high-risk connecting pipe, and judging whether the corrosion resistance and the mechanical property of the high-risk connecting pipe are changed or not based on detection results.

Inventors

SONG XIAOJUN
ZHU ENXIONG
WEI XIYAO
DENG DEHAI
LI LINJIE
GUO RUIPENG
WANG BOHUA
DENG ZHIWEI
MA HUIPING
LIU NAN
WANG WEILI
YANG ZHONGWU
WANG PAN
LIU SHAODONG
ZHANG HUIWEI

Assignees

中国石油天然气股份有限公司

Dates

Publication Date: 20260512
Application Date: 20241111

Claims (10)

1. The safety evaluation method for the stainless steel forging connection pipe of the in-service pressure vessel is characterized by comprising the following steps of: setting a plurality of safety evaluation indexes of stainless steel forging connection pipes of in-service pressure vessels, and setting the duty ratio weight and interval coefficient of each safety evaluation index; Calculating the actual duty ratio of each safety evaluation index according to the environment in which the stainless steel forging adapter of the pressure vessel is used, wherein the actual duty ratio is calculated in such a way that the duty ratio weight of the same safety evaluation index is multiplied by an interval coefficient; and when the sum of the actual proportion of each safety evaluation index is more than 60%, judging that the stainless steel forging connection pipe of the in-service pressure vessel belongs to a high-risk connection pipe, and completing the safety evaluation.
2. The method for evaluating the safety of in-service pressure vessel stainless steel forging connection pipes according to claim 1, wherein the safety evaluation indexes of the plurality of in-service pressure vessel stainless steel forging connection pipes comprise: the service time, the operating pressure, the operating temperature, whether the medium is corrosive or not, whether the repairing exists in the manufacturing process or not and whether the position of the stainless steel forging connecting pipe of the in-service pressure vessel is arranged at the bottom of the pressure vessel or not.
3. The safety evaluation method for the stainless steel forging connection pipe of the in-service pressure vessel according to claim 2, wherein the duty ratio weights of the safety evaluation indexes are respectively as follows: The weight of the service time is 20%, the weight of the operating pressure is 10%, the weight of the operating temperature is 10%, the weight of the medium is 30% whether corrosive, the weight of the medium is 15% in the manufacturing process, and the weight of the medium is 15% in the bottom of the pressure container.
4. The safety evaluation method for the stainless steel forging connection pipe of the in-service pressure vessel according to claim 2, wherein the interval coefficients of each safety evaluation index are specifically: the service time is expressed as A, the unit is year, when 0<A is less than or equal to 5, the interval coefficient is 0.5, when 5<A is less than or equal to 10, the interval coefficient is 0.75, and when A is more than or equal to 10, the interval coefficient is 1; The operating pressure is expressed as B, the unit is Mpa, the interval coefficient is 0.5 when 0<B is less than or equal to 1.6, the interval coefficient is 0.75 when B is less than or equal to 1.6 and less than or equal to 10, and the interval coefficient is 1 when B is more than or equal to 10; The operation temperature is expressed as C, the unit is the temperature, when C is more than or equal to 40, the interval coefficient is 1, when C is less than 40, the interval coefficient is 0; The interval coefficient is 1 when the medium is corrosive, and 0 when the medium is not corrosive; When there is repair in the manufacturing process, the interval coefficient is 1, when there is no repair in the manufacturing process, the interval coefficient is 0; The interval coefficient is 1 when the position is set at the bottom of the pressure vessel, and 0 when the position is not set at the bottom of the pressure vessel.
5. A method of inspecting an in-service pressure vessel stainless steel forging nipple based on the safety assessment method of any one of claims 1-4, comprising: when the stainless steel forging connection pipe of the in-service pressure vessel is judged to belong to a high-risk connection pipe, carrying out nondestructive testing on the high-risk connection pipe; And after the nondestructive testing is finished, carrying out on-site metallographic film coating detection on the high-risk connecting pipe, and judging whether the corrosion resistance and the mechanical property of the high-risk connecting pipe are changed or not based on a detection result.
6. The method for inspecting a stainless steel forging nipple for an in-service pressure vessel according to claim 5, wherein the nondestructive inspection includes ultrasonic wall thickness inspection, fillet ultrasonic nondestructive inspection, nipple outer surface defect inspection, and nipple inner surface inspection.
7. The method for inspecting an in-service pressure vessel stainless steel forging nipple according to claim 6, wherein the nipple external surface defect inspection comprises magnetic powder inspection and penetration inspection.
8. The method of inspecting an in-service pressure vessel stainless steel forging nipple of claim 5, wherein the nipple interior surface inspection includes visual inspection and endoscopic inspection.
9. The method for inspecting a stainless steel forging nipple of an in-service pressure vessel according to claim 6, wherein the on-site metallographic film coating inspection specifically comprises: Pretreating the surface of the high-risk connecting pipe, softening the complex film material by using a softening solvent to obtain a complex film, contacting the complex film with the pretreated surface of the connecting pipe, pressurizing to enable the material on the complex film to flow so as to fill in the relief of the image on the grinding surface, copying a metallographic image, and taking the complex film back to a laboratory for observation by using a high-power microscope after the complex film is finished.
10. The method for inspecting a stainless steel forging connection pipe for an in-service pressure vessel according to claim 5, wherein the pretreatment comprises grinding, polishing and corrosion sequentially, wherein a corrosive agent used for the corrosion is prepared from nitric acid, hydrochloric acid and water according to a volume ratio of 1:3:1, and the composite film material is AC paper.

Description

Safety evaluation and inspection method for stainless steel forging connection pipe of in-service pressure vessel Technical Field The invention belongs to the technical field of special equipment inspection and detection, and relates to a safety evaluation and inspection method for stainless steel forging connection pipes of in-service pressure vessels. Background In the petroleum and natural gas exploitation process, a plurality of pressure containers are needed to process oil gas so as to meet the oil gas conveying requirement, and the pressure containers are selected according to the physical properties and the technological requirements of media of different blocks. In the manufacturing process of pressure vessels used in the petroleum and natural gas industry, in order to improve the corrosion resistance of the connecting pipe part, stainless steel forging materials are often selected to be used as connecting pipes, and particularly in the manufacturing process of composite plate pressure vessels, the stainless steel is difficult to build up in the connecting pipes with small pipe diameters (less than or equal to 50 mm), so that the connecting pipes of stainless steel forging are difficult to avoid. The problems in the use process of the stainless steel forging connecting pipe are that 1) as the common stainless steel forging materials such as 304, 316L and 2205 have sensitization temperature (the interval is 427-816 ℃), when the heating temperature reaches the interval and stays, harmful phases among forging tissue crystals can be separated out, in the manufacturing process of a pressure container, the stainless steel forging connecting pipe needs to be subjected to heating solution treatment before welding, is influenced by welding heat in the welding process, and also needs to be subjected to integral heat treatment with the pressure container after the welding is finished, and in the three heat treatment processes of solution treatment, welding and integral heat treatment, the common temperature exceeds or reaches the sensitization temperature interval, so that the corrosion resistance of the stainless steel forging connecting pipe can be reduced to a certain extent, and the physical and chemical property analysis of the stainless steel forging connecting pipe is not needed after the manufacturing of the pressure container; 2) the welding of stainless steel forging connection pipes and container barrels belongs to dissimilar metal welding, chemical components, structures, performances and stress fields existing in a welding line area are uneven, corrosion resistance and mechanical property reduction of the stainless steel forging part area can be caused, 3) according to the rule of petroleum and natural gas exploitation, water, chlorine radicals and temperature in a medium can be increased along with time, corrosiveness of the medium can be enhanced, a pressure container through which the medium flows faces larger corrosion risks, 4) according to the rule of fixed pressure container safety supervision technical regulations (TSG 21-2016), connection pipes less than or equal to 150mm are not main compression elements of the pressure container, are easily ignored in the periodic inspection process, even if users require inspection, and conventional nondestructive inspection methods such as ultrasonic waves, permeation and the like are used, defects in the aspect of physical and chemical properties of the stainless steel forging connection pipe are difficult to detect, and the stainless steel forging connection pipe cannot be comprehensively evaluated. In summary, the stainless steel forging connection pipe is a high risk point of the pressure vessel, but the existing inspection method cannot comprehensively grasp the defect condition of the stainless steel forging connection pipe of the in-service pressure vessel, and cannot reflect the physicochemical performance index of the connection pipe under the condition of not damaging the connection pipe. Disclosure of Invention The invention aims to solve the technical problems that the inspection method of the pressure vessel connecting pipe in the prior art is difficult to detect the defects of the stainless steel forging connecting pipe in terms of physicochemical properties and cannot comprehensively evaluate the stainless steel forging connecting pipe, and provides a safety evaluation and inspection method of the stainless steel forging connecting pipe of an in-service pressure vessel. In order to achieve the above purpose, the invention is realized by adopting the following technical scheme: in a first aspect, the invention provides a safety assessment method for an in-service pressure vessel stainless steel forging connection pipe, comprising the following steps: setting a plurality of safety evaluation indexes of stainless steel forging connection pipes of in-service pressure vessels, and setting the duty ratio weight and interval coefficient of eac