I was on a call last month with a procurement manager from a Central Asian operator who needed to order spare parts for a wellhead system. He had the API spec, the P&ID drawing, and a grainy photo. What he did not have was a clear parts breakdown. That call is why I am writing this. Here is a practical breakdown of every major wellhead component, what it does, and how to identify it from the spec sheet.
The Wellhead System: Bottom to Top
Complete wellhead system, from the ground up: Casing Head (foundation, welded onto surface casing) → Tubing Head (supports the tubing string, provides side outlets) → Christmas Tree (valve assembly that controls production). I have seen operators refer to the entire assembly as a Christmas tree when they really mean the wellhead system. Be specific about which section you are ordering for.
Casing Head Components
Bowl/Housing (load-bearing body, 4130/4140 forged steel), Casing Hanger (supports casing weight — slip-type or mandrel-type), Bowl Weld Preparation (bottom bevel for welding to casing), Side Outlets (2-1/16" or 2-9/16" API threaded or flanged), Lockdown Screws (secure hanger after cementing). Ring gaskets (RX/BX type, soft iron or 316SS) seal the flange connections.
Tubing Head and Christmas Tree Parts
Tubing Head (single-body, moderate pressure) or Tubing Spool (taller, with upper/lower flanges). Tubing Hanger (supports tubing string weight — match thread type, size, and material class). Christmas Tree: Lower Master Valve, Upper Master Valve, Flow Cross, Wing Valves (flow wing + kill wing), Swab Valve (wireline/coiled tubing access), Top Connector.
Wellhead equipment is straightforward once you understand the stack: casing head supports the first string, tubing head supports the tubing, Christmas tree controls the flow. Each connection uses a ring gasket that should be replaced every time the connection is broken. Send photos or spec sheets to JLD Energy if you need help identifying a component.
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Frequently Asked Questions
Difference between casing head and tubing head?
How to identify the correct ring gasket?
Most commonly replaced wellhead part?
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