Wellhead and Christmas Tree Inspection: The Pressure Boundary Nobody Watches

After the rig moves off, the wellhead and the Christmas tree stay. They hold the pressure of the well for decades, in the weather, with nobody watching them daily. The equipment that was on location for a month gets inspected weekly; the equipment that will hold the well for thirty years gets inspected when someone remembers.

What the wellhead actually is

The wellhead is the permanent pressure boundary of the well: the casing head, the tubing head, and the connections that seal the casing and tubing strings to the surface. On top of it sits the Christmas tree, the assembly of valves and fittings that controls the flow. Between the two, the seals and flanges are the quiet components that hold the pressure, and they fail quietly too: a leaking connection, a corroded stud, a valve that will not close all the way.

The casing and cementing article on this site covers how the well is built to the surface. The wellhead is the end of that story and the beginning of the production story, and it gets the least attention of either.

What the inspection covers

The inspection list is short and physical. The casing head and tubing head, for damage and corrosion. The flanges and studs, for the tension and condition that hold the seal. The valves on the tree, for operation and for leaks: the master valves, the wing valves, the kill side. The seals and packing, for age and wear. Signs of corrosion, especially where the weather and the well fluids meet. The lock screws and the fittings that have not been touched since installation day.

The preventive maintenance article on this site covers why the schedule decays: the equipment is out of sight, the routine is boring, and the failure is years away. The wellhead is the purest case of that dynamic, because it is invisible until the day it is not.

The records that make it real

A wellhead file has three parts. The certificates: the API 6A documentation with the pressure ratings for every component. The installation records: what went in, when, with what torque and what test. The inspection and test records: the pressure tests, the inspections with dates and findings, the repairs. Together they tell the story of the boundary that holds the well.

The field reality is that the certificates are in a file in the office, the installation records are in another file, and the inspections are in a notebook on location, if they exist. The operator who knows exactly what is on every wellhead is rare, and that knowledge is worth money the day a leak appears, because the first question is always the same: what is this equipment rated for, and when was it last tested?

The pressure test as the proof

The tree is pressure tested on installation and after major work, and the test is the proof that the boundary holds. The record of the test, with the pressure, the hold time, and the witness, is the document that answers the auditor and the emergency responder alike. The same discipline runs on the drilling side, and the BOP testing article covers it there: the test only matters if the record survives.

The valve that never moves is the one that fails

Tree valves sit in one position for years, and a valve that never operates is a valve that will not operate when it matters. The periodic exercise is part of the wellhead routine: open and close the valves on a schedule, check the seals, note the torque and the condition, and record the result. The exercise catches the seized stem, the leaking packing, and the corrosion that the static valve hides.

The record of the exercise is the same kind of file as everything else on the boundary: date, valve, condition, signature. The wellhead that has a file is the wellhead that gets maintained. The one without a file is the one that gets remembered too late.

If your wellhead files are scattered across a filing cabinet and a notebook, book a working session with the OpsFlo operations team. Book a call here to keep wellhead certificates, test records, and inspections per well, so the boundary is documented as well as it is sealed.