(materials, dimensions, test procedures and pressure ratings etc.) are : API 6A, 20th Edition, October 2010; Specification for Wellhead and Christmas Tree Equipment ISO 10423:2009 Wellhead and Christmas Tree Equipment In general well heads are five nominal ratings of wellheads: 2, 3, 5, 10 and 15 (x1000) psi working pressure. They have an operating temperature range of -50 to +250 degrees Fahrenheit. They are used in conjunction with ring type seal gaskets. In general the yield strength of the materials range from 36000 to 75000 psi. See also Puteal — Water well head Pumpjack American Petroleum Institute Drilling rig (petroleum) References External links Schlumberger Oilfield Glossary: wellhead Oil wells Oil platforms Petroleum production Oilfield terminology