Effects of Make-Up Torque on the Sealability of Sphere-Type Premium Connection for Tubing and Casing Strings

Abstract

The present investigations on sealability evaluation for tubing and casing premium connections depend on the FEM with testing. This paper proposed a theoretical model to evaluate the sealability of a sphere-type premium connection based on make-up torque, which combines Hertz contact pressure and the von Mises yield criterion for calculating elastic–plastic contact pressure distribution on sealing interface and adopts the gas sealing criterion obtained from Murtagian’s experimental results for deducing gas sealing capacity. With the proposed model, the effects of additional make-up torque from the sealing interface on the sealing contact pressure distribution and key sealability parameters, including contact width, yield width, average contact pressure and gas sealing capacity, were analyzed and compared. The results show that additional make-up torque from the sealing interface closely influenced sealability parameters’ variation and gas sealing capacity. The gas sealing index based on the sealing contact energy theory should be recommended for sealability evaluation other than average contact pressure on the sealing interface. For improving gas sealability, make-up torque should be controlled accurately for ensuring enough average contact pressure and contact width but a proper yield width, and a lager sphere radius should be selected for reducing the risk of yield sticking.

An Improved AoT-DCGAN and T-CNN Hybrid Deep Learning Model for Intelligent Diagnosis of PTCs Quality under Small Sample Space

“…three phases: gradual increase, significant increase, and rapid increase, representing the thread interference, metal-to-metal sealing, and torque shouldering sections, respectively [8]. However, during real make-up processes, abnormalities in the PTCs curve may appear due to misalignment or thread damage, as demonstrated in Figure 2b,c.…”

“…The current primary method involves the manual inspection of torque curves generated during PTC connections to identify damage or correct connections [4][5][6][7]. However, manual inspection relies heavily on the professional background and work experience of field engineers, leading to a lack of objectivity and quantifiability in the evaluation [8]. Therefore, achieving intelligent diagnosis of PTCs quality necessitates automatic classification and recognition of PTCs curves under different connection conditions.…”

Modeling Surface Roughness and Flow of Gases in Threaded Connections to Analyze Sealing Performance

“…For the make-up process of the premium connection, it is important to determine the optimum make-up torque. Figure 4a shows the theoretical shape of the make-up torque [26], involving three distinct stages of the torque evolution. The first stage starts with the thread interference, giving rise to a linear increase of the torque from zero (stage AB); the second stage begins with the seal surface interference leading to a slightly faster linear increase of the torque (stage BC); the third stage is characterized by a much higher slope of the torque increase due to the shoulder interference (stage CD).…”

Study on Sealing Performance of Airtight Buckle Under Complex Loads

“…Yu et al (2022) has proposed a semi-theoretical and semi-empirical model to analyze the influence of internal pressure and axial force on the sealing performance. Moreover, Yang et al (2023) has established a sealing performance evaluation model by the Hertz theory and von Mises yield criterion, the influence of the additional torque from sealing interface on the distribution of sealing contact stress and key sealing parameters, including contact width, yield width, average contact stress, and gas sealing capability, is explored. Although theoretical methods can quantitatively investigate the effect of simple loads on the mechanical performance of seal connections, it is also challenging to study the mechanical performance of the joints accurately under complex loading conditions.…”