Drilling Fluid Circulation Manifold (referred to as the High Pressure manifolds) is one of the main equipment for the high pressure jet drilling, it will discharge the high-pressure mud pump mud introduced into the well, cleaning the bottom, carrying the debris to complete the drilling process, and with cementing and other operations. The product is easy to operate, high pressure, Manifolds GM, connection flexible.
In recent years, domestic drilling companies supporting a large number of High Pressure manifolds, are 35MPa level. As well, the number of wells drilled increased complexity, also will increase the pressure of drilling, drilling companies have proposed various 70MPa High Pressure manifolds level of demand. To take this opportunity, take advantage of years of conventional High Pressure manifolds of design and production experience, self-developed 70MPa even higher level of High Pressure manifolds, in strict accordance with the Ministry of Oil production standards and API standards.
Manifolds withstand 70MPa pressure, the weld is its weak link, and therefore how to improve the welding process, improve weld quality, ensure that the weld strength to meet the design requirements, through improved technology, the weld reach PSL3 specification level, withstanding a test pressure of up to 105MPa and through magnetic, ultrasonic and radiographic inspection, become 70MPaHigh Pressure manifolds in the production of major technical problems. On this basis, in order to ensure product quality, increase production efficiency.
1. Summary of the research results
In order to improve the bearing strength Drilling Fluid Circulation Manifold solve the problem of sealing and strength properties of pressure parts; to ensure weld quality, solve the problem of pressure parts welding technology, research side welding technology; To make Drilling Fluid Circulation Manifold stable under high pressure to solve the problem of welding process and sealing performance under high pressure; development of various rigs models applicable High Pressure manifolds and various structures High Pressure manifolds, including single riser, double risers, removable valve groups, etc., in order to expand the product range.
70MPa Drilling Fluid Circulation Manifold body still uses low pressure level Drilling Fluid Circulation Manifold same 1003 Spherical Hammer Uniom, keeping the overall structure Manifolds allow rapid loading and unloading, the entire Manifolds various parts interchangeability, disassembly fast, and allows tilt ± 8 ° characteristic use. Ground pipelines and risers can be divided into several sections, allowing the use of self-adjusting according to the actual situation of the well site, which requires the connector to solve the problem bearing strength of the structure, materials, technology and other aspects.
The main technical parameters:
Model: ZG102-70
Rated working pressure: 70MPa
Nominal diameter: 102mm
Operating temperature range: -29 ~ 121 ℃
Control: Manual
Connection: Hammer Uniom
Sealing test pressure: 70MPa
Strength test pressure: 105MPa
2. Material specifications and pipelines strength calculation
70MPaDrilling Fluid Circulation Manifold need to analyze and calculate the four areas.
1) Check the pipeline at different load conditions of stress testing, installation, operation and other relevant standards can meet the requirements of this part was analyzed by specialized software.
2) Check the pipe wall thickness piping design chosen meets the requirements.
3) Determine the reaction forces at the line support structure, this reaction is extracted and applied to structural framework, the structural framework of the corresponding analysis calculated under different working conditions.
4) pipe pressure drop calculations.
2.1 Material Specifications
70MPaDrilling Fluid Circulation Manifold use made of 35CrMo steel, high rupture strength and creep strength at high temperature 35CrMo steel, low temperature impact toughness is good, high temperature operating temperature up to 500 ℃, low temperature to -110 ℃, and has a high static strength, impact toughness and high fatigue strength, good hardenability, no overheating tendencies, quenching
Thermal deformation, cold deformation toughness is acceptable medium machinability; but first temper brittleness, good weldability, preheating before welding to 150 ~ 400 ℃, post weld heat treatment to eliminate stress, general After the modulation process, it can also be in the high-frequency surface hardening or quenching and low temperature tempering use. All High Pressure manifolds material steel execution GB / T8162-1999 "structure with a seamless" standards and norms, provided can meet the -29 ~ 121 ℃ operating temperature, High Pressure manifolds pipe specifications φ140mm × 19 mm, inside and outside diameter size tolerance 0 ~ -0.2m, the body must be quenched and tempered steel, hardness of 197 ~ 229HB, after degaussing, and do all the ultrasonic flaw detection.
2.2 Pipeline strength calculations
Pipe wall thickness calculation
δ = pDn / (2 [σ] ψ-p) = 70 × 102 / (2 × 326.67 × 0.9-70) = 13.78
Where: δ is calculated pipe wall thickness, mm; p design pressure, MPa; Dn for the pipe diameter, mm; ψ welding factor, taking 0.9; [σ] t is the material the design temperature allowable under stress, according to Rm / nb and Rd / n, whichever is the smaller value is determined, MPa.
Among them:
Rm / nb = 980/3 = 326.67
Rd / ns = 835 / 1.65 = 506.06
Where: Rm of the material at the design temperature t of tensile strength, MPa; Rd for the material yield strength at design temperature t, MPa; nb safety factor of tensile strength index at room temperature take 3.0; ns the safety factor for the yield strength index, at room temperature taking 1.65.
Pipeline design wall thickness:
δs = δ + C1 + C2 = 13.78 + 1 + 2.5 = 17.28
Where: design of the pipe wall thickness δs, mm; C1 of pipe wall thickness negative deviation value, mm, according to pipe standard specifies the value; C2 to corrosion allowance of pipe wall thickness, mm, Richard C2 = 2.5.
3. Process Design
70MPaHigh Pressure manifolds having the characteristics of high pressure, so the weld strength have higher requirements, and welding needs after magnetic particle inspection, ultrasonic inspection, radiographic inspection and hydrostatic strength test detection qualified to delivery. 70 MPaHigh Pressure manifolds weld strength test pressure of 105MPa, so the high pressure welding seam welding process research and technology and ultimately the use of welding side welding technology, weld forming the back straight, while ensuring that the entire weld The appearance of quality and mechanical properties.
Thus, process design to achieve greater focus on the quality of welding, welding efficiency and product qualification rate method detailed control of the welding process requirements and process parameters. Welding process diagram shown in Figure 1, the welding parameters are shown in Table 1.

Figure 1 Welding Technology
Welding parameters in Table 1

Currently used in welding technology can weld the 1st forming a pass rate of more than 99% more than traditional welding process 1 forming the weld pass rate increased by 29%. The process which has six advantages:
1) welding efficiency is good, no further on the back of slag, gouging, significantly reducing the use of consumables.
2) forming a smooth uniform weld appearance, more than sufficient to ensure a high quality and appearance.
3) improve weld quality than in the past, there have been a dozen of Manifolds of weld inspection of 100% of the standard Ⅰ, Ⅱ type of weld requirements.
4) reduce labor intensity.
5) reduce dependence on the skills of the welder, reduce processing costs.
6) reduces rework costs, the overall cost (labor, consumables, electricity, etc.) to save more than 50%.
4. Conclusion
1) The level of 70MPa Drilling Fluid Circulation Manifold material specifications, sealing solutions and process analyzes, has been calculated to meet the overall design requirements.
2) 35CrMo, 140mm × 19mm pipe welding process Manifolds body, high compressive strength, good weldability; use 1003 Spherical Hammer Uniom connection, good sealing performance, easy accessibility, interchangeability. The Manifolds with a wide range of application, can be used as standard rig equipment.
3) Scope 70 MPaDrilling Fluid Circulation Manifold wide, can improve the level of drilling rig, rig improve our overall competitiveness.