Measurement of Fugitive Emissions of Industrial Valves

Abstract

Against the background of the reduction of fugitive emissions, the demands on industry are increasing, steadily. In Europe the Integrated Pollution Prevention and Control (IPPC) directive [1] determines emission levels for different industrial facilities. Member countries must adopt these specifications into national guidelines like in Germany the TA-Luft (“Technical Instructions on Air Quality Control”) [2]. In addition, the German VDI guideline 2440 (“Emission control - Mineral oil refineries”) [3] gives more detailed procedures to meet the requirements. Apart from this qualification test in VDI 2440 in Germany, some other (more comprehensive) test procedures are established worldwide to examine the mechanical and tightness behavior of the packing material in valves. These test procedures are e. g. API 622 [4] or ISO 15848-1 [5]. The different test parameters of these test standards are compared in this paper with the ones of the VDI guideline 2440. Also, some typical test results of the VDI 2440 testing shall be illustrated and discussed in respect on the transferability to the other standards. Because the test procedures in the standards are different, it is not possible to perform the test on the same testing device. Especially the added requirement in ISO 15848-1 to measure the tightness of the body joint, leads to additional requirements on the testing equipment. In addition to the well-established test rig for the characterization of the mechanical and tightness properties of the packing material, a new testing device for valves is introduced. With this equipment, the stuffing box packing and the body seal of valves can be tested. The measurement of the friction forces during the stem cycles and the determination of the tightness characteristics (with Helium or Methane) are in the focus of the investigations of this test bench.

Valve design considerations in liquid hydrogen systems to prevent failure

“…In order to reduce fugitive emissions, or emissions coming from industrial valves, including cryogenic hydrogen valves, the stem seals must be able to seal effectively and have a long life. [43,44,45,46] A valve leak can be classi ed as an internal leak from the valve seat and an external leak from the stem seal area. It is more hazardous to have external leakage from the stem seal area since it may contact personnel working in the valve area or could leak into the environment.…”

“…For non-cryogenic applications, elastomeric seals such as nitrile rubber, hydrogenated nitrile and silicon, and Viton are commonly used to seal valve stems. [43,44,45,46,47] Nevertheless, none of these seals can be used at cryogenic temperatures.…”

“…For the stem sealing of liquid hydrogen cryogenic valves, valve engineers can choose graphite packing. [35,43] PTFE is a very common soft material for seats of industrial valves in the oil and gas industry. However, since the minimum temperature for PTFE is -46℃ according to some standards and speci cations such as NORSOK (Norwegian petroleum standards), [35,44,48,49,50] Cryogenic hydrogen valves do not commonly use PTFE as a non-metallic material.…”