Polished rod clamps to grip the polished rod and carry the rod string load from the pumping unit, in sizes from 3/4 inch to 1-1/2 inch.
- Standard: API 11B, API 11BR, ASTM A29
- Grades: C, D, K, KD
Specifications
| Outer diameter | For 3/4" - 1-1/2" polished rods |
|---|---|
| Length | Per clamp type and rod size |
| Ends | Bolted clamp with hardened slips |
| Surface treatment | Painted or zinc coated |
| Manufacturing process | Forged and machined, slips hardened |
| Connection type | Bolted clamp, single or double bolt |
How a Polished Rod Clamp Works
The polished rod clamp is the component that transfers the entire weight of the rod string to the pumping unit. It clamps onto the polished section of the polished rod above the carrier bar, and its hardened slips bite into the rod surface to hold it against the load. Because this is the point at which the whole string load is carried, the clamp is a safety critical item and its condition and correct tightening matter greatly. Over-tightening crushes the rod surface and creates a stress riser that can cause the polished rod to break at that point; under-tightening allows the rod to slip through the clamp, dropping the string. The clamp should be installed with the specified bolt torque and inspected regularly for slip wear. Any visible damage to the polished rod in the clamp area is a reason to cut and re-dress the rod rather than to re-clamp over it.
Single Bolt and Double Bolt Clamps
Polished rod clamps come in single bolt and double bolt designs. A single bolt clamp has one bolt and relies on the wedge action of the slips for grip; it is quick to install and adjust and is used in lighter duty applications. A double bolt clamp has two bolts and gives a more even grip and a higher holding capacity, and is used where the rod string is heavy or the well is deep. Some designs also incorporate a hinged or a slip-in retaining feature so the clamp can be installed without lifting the string. Whichever type is used, the clamp must be matched to the polished rod diameter and to the load, and the specified torque must be applied rather than relying on feel.
How tight should a polished rod clamp be?
Tighten the clamp bolts to the torque specified by the manufacturer for that clamp and rod size. Over-tightening is a common and serious error: the slips crush the rod surface and create a stress riser where the polished rod can later break under load. Under-tightening allows the rod to slip. Always use a torque wrench, and inspect the polished rod in the clamp area whenever the clamp is moved.
When should I replace a polished rod clamp?
Replace the clamp when the slips are worn to the point that they no longer grip reliably, when the clamp body or bolts show cracks, deformation or corrosion pitting, or when the clamp has slipped and damaged the rod once. Because the clamp carries the full string load, any doubt about its condition is a reason to replace it. Inspect slips and bolts at each workover.
Materials
- Forged carbon steel
- Alloy steel
- Hardened steel slips
Typical applications
- Securing the rod string to the pumping unit carrier bar
- Carrying the rod string load at the wellhead
- Adjusting the rod string position on the pumping unit
- Well servicing and rod string handling
Inspection & testing
- Dimensional inspection
- Slip hardness testing
- Load and proof testing
- Material certification
- Visual and magnetic particle inspection
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