1. For pipeline systems and equipment handling low-temperature media, low-temperature needle valves with bonnets are recommended.
2. For pipeline systems in catalytic cracking units of oil refining plants, rising stem needle valves can be used.
3. For equipment and pipeline systems handling corrosive media such as acids and alkalis in chemical systems, all-stainless steel needle valves made of austenitic stainless steel with PTFE seat seals are recommended.
4. For pipeline systems or equipment handling high-temperature media in metallurgical systems, power systems, petrochemical plants, and urban heating systems, metal-to-metal sealed needle valves can be used.
5. When flow regulation is required, worm gear driven, pneumatic or electric regulating needle valves with V-shaped openings can be used.
6. For main oil and natural gas transmission pipelines that require pipeline cleaning and are buried underground, full-bore, fully welded needle valves should be selected; for those buried above ground, full-bore welded or flanged ball valves should be selected.
7. For refined oil transportation pipelines and storage equipment, flanged needle valves should be selected.
8. For city gas and natural gas pipelines, both flanged and threaded needle valves should be selected.
9. In oxygen pipeline systems within metallurgical systems, flanged needle valves that have undergone rigorous degreasing treatment are recommended.