Abstract
High-pressure steam gate valves are critical isolation barriers in petrochemical units, especially during shutdowns, emergency isolation, and major maintenance. This paper presents a practical failure analysis and maintenance improvement case involving two large gate valves installed in series on the high-pressure steam line of an ethylene cracking unit. The valves operated in superheated steam service at approximately 525 °C and 12 MPa and had experienced recurrent leakage after overhaul. Based on maintenance history, disassembly inspection and operating feedback, the dominant external leakage path was identified as the upper sealing system, including the backseat, stem, packing and self-sealing region. The root causes included backseat deformation under steam erosion, excessive stem clearance, thermal fatigue and scoring of the stem, insufficient packing resistance to thermal settling and steam attack, and limited maintainability of the original metallic self-sealing arrangement. Corrective actions included redesigning the backseat as a more rigid 45° line-contact sealing head, upgrading the stem material and reducing the diametral clearance from approximately 3 mm to 0.5 mm, increasing the stuffing box depth from 140 mm to 167 mm, adopting a composite reinforced graphite and metal-support packing structure, and replacing the original hard self-sealing concept with a more tolerant graphite-based sealing arrangement. Preventive maintenance was also performed on the wedge and actuator, and staged hot retightening was applied during startup. Post-overhaul inspection and operating feedback indicated that the repaired valves met the required technical criteria and no visible leakage was observed during subsequent site operation. The case shows that recurrent leakage in severe steam service should be addressed as a complete sealing-system problem rather than as an isolated packing failure.
References
[1] Yao HY, Jiang CH, Jin ZJ, Qian JY. Research progress on valve failure. Fluid Mach. 2021;49(10):74-83, 90.
doi:10.3969/j.issn.1005-0329.2021.10.011.
[2] Smith P, Zappe RW. Valve selection handbook: engineering fundamentals for selecting the right valve design for every industrial flow application. 5th ed. Amsterdam: Gulf Professional Publishing; 2004.
[3] ASME. ASME B16.34-2025: valves—flanged, threaded, and welding end. New York: American Society of Mechanical Engineers; 2025.
[4] Sotoodeh K. A review of valve stem sealing to prevent leakage from the valve and its effect on valve operation. J Fail Anal Prev. 2021;21(1):9-16.
doi:10.1007/s11668-020-01050-1.
[5] API. API Standard 600: steel gate valves—flanged and butt-welding ends, bolted bonnets. 14th ed. Washington, DC: American Petroleum Institute; 2021. Errata 1, 2024.
[6] Kishore K, Kushwaha S, Lal D, Sharma A, Prabhakaran A, Adhikary M, et al. Failure investigation of a hot blast valve of stove of blast furnace. J Fail Anal Prev. 2021 Jul 14.
doi:10.1007/s11668-021-01200-z.
[7] API. API Standard 622: type testing of process valve packing for fugitive emissions. 3rd ed. Washington, DC: American Petroleum Institute; 2018. Addendum 1, 2022.
[8] Chen YQ, Yu H, Fu SW, Li A. Study on sealing performance of main gate valve of marine nuclear power plant based on fluid-solid-thermal coupling method. Front Energy Res. 2024;12:1375806. doi:10.3389/fenrg.2024.1375806.
[9] Bickford JH. Introduction to the design and behavior of bolted joints: non-gasketed joints. 4th ed. Boca Raton, FL: CRC Press; 2007. doi:10.1201/9780849381874.
[10] API. API Standard 598: valve inspection and testing. 11th ed. Washington, DC: American Petroleum Institute; 2023.
[11] ISO. ISO 5208:2015: industrial valves—pressure testing of metallic valves. 4th ed. Geneva: International Organization for Standardization; 2015.
[12] MSS. MSS SP-61-2019: pressure testing of valves. Vienna, VA: Manufacturers Standardization Society of the Valve and Fittings Industry; 2019.
How to cite this paper
Failure Analysis and Maintenance Improvement of a High-pressure Steam Gate Valve in Superheated Steam Service
How to cite this paper: Jingdi Wu. (2026). Failure Analysis and Maintenance Improvement of a High-pressure Steam Gate Valve in Superheated Steam Service. Engineering Advances, 6(3), 167-172.
DOI: http://dx.doi.org/10.26855/ea.2026.09.007