Pup Joints

Casing Pup Joints:

Outside Diameter: 4 ½ inch – 13 3/8 inch
Typical Lengths: 1, 2, 3, 4, 6, 8, 10, 12 ft

Grades: H40, J55, K55, N80, L80 T95, C110, P110 Connections: SC, LC, BC, Semi Premium, and Premium

Tubing Pup Joints:
Sizes: 2 ⅜ inch  – 4 ½ inch
Typical Lengths: 1, 2, 3, 4, 6, 8, 10, 12 ft
Grades: J-55, N-80, L-80, P-110
Connections EU (external-upset) and NU (non-upset)

Pup Joint Options:

Connection Types of Pup joints: 

1. API Threaded Pup Joints
The most common pup joint connections conform to API 5CT specifications. API threaded joints use tapered threading that provides high strength and pressure resistance for casing and tubing strings. The tapered thread form consists of symmetric V-shaped wedges that create tight seals under increasing loads. This self-locking characteristic prevents joints from loosening over repeated thermal cycles in harsh downhole environments.

2. EUE Pup Joints
The EUE or external flush threaded connection uses exterior male threads on the pin end that mate with female threads on the box coupling.This design provides a flush outer diameter without recessed threads for unobstructed string installation. EUE threads minimize flow restrictions and turbulence for optimal hydraulic performance.

3. NUE Pup Joints
NUE joints feature female threads machined on the interior walls of the pin end. Corresponding male wedge threads on the coupling provide the sealing force. The smooth outer pin nose facilitates alignment and initial engagement during stabbing.

4. BTC Pup Joints
Buttress threaded connections or BTC represent another common joint variant defined by API 5CT standards. BTC threads utilize angled flanks with substantially increased clamping force and interference compared to API round threads. This provides superior resistance to axial loads and internal pressures.

5. STC Pup Joints
Shoulder threaded connections or STC joints use a multi-stepped thread profile. The design alternates between larger and smaller diameter sections which create axial shoulders. This step profile allows rapid initial mating followed by high torque final tightening to achieve strong sealing and assembly integrity.