Zn-Ni Plated Pipe Threads for Grease-Free Galling Resistance

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing threaded connections for pipes face challenges in achieving sufficient galling resistance without using heavy metal-containing greases, as conventional solutions do not consistently provide adequate resistance to friction during repeated fastening and unfastening.

Innovation Solution

A threaded connection for pipes is developed with a Zn—Ni alloy plating layer on the contact surfaces of the pin and box, containing trace amounts of chromium, which is formed through an immersion and current conduction process in a plating solution with zinc, nickel, and chromium ions, enhancing the hardness and galling resistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If heavy metal-containing compound greases are used to improve galling resistance, then the galling resistance of the threaded connection is improved, but heavy metals may affect the environment

Engineering Contradiction:

Improvegalling resistanceVSAvoidenvironmental impact

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention extracts and removes the harmful heavy metal components from the lubricating grease, replacing them with environmentally friendly alternatives while maintaining the necessary galling resistance through a different chemical composition that does not include heavy metals like lead

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The invention changes the chemical composition parameters of the lubricating grease by specifying a particular formula without heavy metals, while maintaining the functional properties needed for galling resistance through alternative lubricating mechanisms and additives

Inventive Principle:

Principle #35Parameter changes

2Reliability

If a plating layer is formed on the contact surface to improve galling resistance, then the galling resistance is improved, but sufficient galling resistance was not always obtained

Engineering Contradiction:

Improvegalling resistanceVSAvoidplating layer quality

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The invention uses a composite plating layer structure consisting of multiple layers with different compositions and functions, combining materials that provide both excellent galling resistance and consistent manufacturing quality through the synergistic effects of each layer

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The invention applies different plating layers to different regions or surfaces of the threaded connection, optimizing each layer's composition and properties for its specific function to ensure both galling resistance and manufacturing precision

Inventive Principle:

Principle #3Local quality

3Adaptability or versatility

If repeated thread fastening and unfastening occur, then the threaded connection can be reused for inspection, but galling will occur if friction resistance is insufficient

Engineering Contradiction:

ImprovereusabilityVSAvoidgalling resistance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The invention applies lubricating grease and forms protective plating layers on the threaded surfaces before any fastening operations begin, creating a preliminary protective barrier that prevents galling during subsequent repeated fastening and unfastening cycles

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention provides beforehand protection against friction and galling by applying lubricating grease and forming protective plating layers that cushion the contact surfaces against the harmful effects of repeated mechanical stress and friction

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The Zn—Ni alloy plating layer with a trace amount of chromium significantly increases the hardness and galling resistance of the threaded connection, providing excellent performance even without heavy metal greases, while also maintaining a good external appearance.

Implementation Method 1

a Zn—Ni alloy plating layer which consists of Zn, Ni, a trace amount of Cr and impurities

Methodology Applied

Scientific EffectElectroplating: Electroplating

Implementation Method 2

a current conduction step in which a current is conducted through at least one of the pin-side contact surface and the box-side contact surface that is immersed in the plating solution

Methodology Applied

Scientific EffectElectrodeposition: Electrodeposition

Data Source

PatentUS11293569B2Threaded connection for pipes and method for producing threaded connection for pipes

Publication Date: 2022.04.05 VALLOUREC MANNESMANN OIL & GAS FRANCE

AI summary

The threaded connection for pipes includes a pin, a box and a Zn—Ni alloy plating layer. The pin has a pin-side contact surface that includes a pin-side thread part. The box has a box-side contact surface that includes a box-side thread part. The Zn—Ni alloy plating layer is formed on at least one of the pin-side contact surface and the box-side contact surface. The Zn—Ni alloy plating layer is consisting of Zn, Ni, trace amount of Cr and impurities. The trace amount of Cr content of the Zn—Ni alloy plating layer is 5.0×10 counts/sec or more in terms of Cr intensity as measured by secondary ion mass spectrometry using O2+ ions as bombarding ions.