PSI - Issue 22

Yufei Li et al. / Procedia Structural Integrity 22 (2019) 43–50 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

46 4

3.2. Introduction of the loads in thermal cycle test The purpose of ISO 13679 thermal cycle test is to evaluate the possibility of joint leakage in simulated service environment by applying thermal cycle, axial load and internal pressure (GB/T 21267-2017). During the thermal cycle, the high-temperature and low-temperature sections are kept at the specified temperature for at least 5 minutes, and the minimum time for each complete thermal cycle is 30 minutes. The loading path of CAL IV thermal cycle test for special threaded tubing joints is shown in Fig. 4.

Fig. 4. Loading Path of Thermal Cycle Test for Premium connections

4. Simulation of sealing ability for premium connection 4.1. Establishment of Finite Element Model for Premium connection

Taking a premium connection of Ф88.9mm × 6.45mm P110 tubing as the research object, the sealing surface of the connection is conical-conical seal, and the design dimension is shown in Table 1. Because of the complexity of the structure and loads, in order to prevent shear self-locking and improve the calculation accuracy while controlling the convergence speed, C3D8R is used, and local mesh refinement is carried out at the contact points, sealing surface and torque shoulder. Fig. 5 is the finite element model of a certain premium connection. The number of meshes of tubing is 42988, and the number of meshes of coupling is 45701.

Fig. 5. Finite element model of premium connection.

Table 1. Dimensions of the premium connection.

Bearing surface angle/°

Guiding plane angle/°

Shoulder angle/°

Thread taper

Number of teeth per inch

-3

10

-15

1:16

5