At RathGibson, we understand that choosing between Welded, Welded & Drawn, or Seamless tubing or pipe can be complex. As part of our on-going commitment to customer service, we have created this page to help to demystify the selection process.
Quality Requirements
When making this selection, the quality requirements, such as corrosion, dimensional limits, and
strength, should be the primary criteria. Frequently, companies select tubing or pipe based on processes,
which may lead to a misrepresentation of one's needs and consequently the choice of a less cost effective
or inappropriate tubing option.
The list below presents the most common qualities that are essential to a wide range of applications.
The list also suggests which product type may best fit the requirement. The
Attributes Summary table seen later in this article also makes suggestions based on attributes. Please note that these suggestions are based on generalizations; the final selection should be based on alloy specifics.
1. OD and Wall Tolerances
a. Telescoping tubes
b. ID/OD machining A — Hydraulic or pneumatic cylinders
c. Bending with ID tooling
Suggestions: For these applications, it has been shown that RathGibson Welded & Drawn tubing and pipe are best suited. For bending applications, RathGibson’s Welded tubing and pipe may be used with special tolerances applied.
2. Wall Tolerances
a. Orbital welding
Suggestions: RathGibson Welded or Welded & Drawn tubing and pipe are ideal for wall tolerances requirements.
3. Extreme consequences of a leak possibly after significant fabrication
a. Air cooled exchanger with high fins installed
b. Lethal service
Suggestions: Before an accurate selection can be made, RathGibson highly recommends that integrity testing, as well as additional non-destructive testing (NDT) be performed, regardless of the tubing type utilized.
4. Aqueous Corrosion
a. General
b. Pitting
c. Stress Corrosion Cracking (SCC)
d. Microbial Induced Corrosion (MIC)
Suggestions: In order to make an educated suggestion on the tubing or pipe type that will best resist corrosion, RathGibson recommends that additional quality requirements always be identified.
5. High Temperature Wasting
a. Oxidizing
b. Sulfidation
c. Carburization
d. Metal Dusting
Suggestions: RathGibson Welded & Drawn or Seamless tubing and pipe can best handle High Temperature Wasting. The specific application will help determine the alloy.
6. Cleanability – Hygienic Applications
Suggestions: RathGibson’s High Purity and Ultra High Purity Welded tubing and pipe are specifically designed for industries with hygienic applications, such as Pharmaceutical, BioPharmaceutical, and Food and Beverage. Seamless tubing and pipe can be specified for use with small diameters.
7. OD Cosmetic
a. Requiring OD Polishing
b. OD compression fittings to seal at high pressure
Suggestions: RathGibson’s Welded tubing and pipe are offered with special
finishes that meet any cosmetic OD requirements. Seamless tubing and pipe for small diameters are also available.
8. ID Cosmetic
a. Hydraulic flare seal ends
Suggestions:
Seamless tubing and pipe from RathGibson will meet your most demanding cosmetic ID requirements. RathGibson also offers Welded tubing and pipe that are ID polished that also fit this need.
Attributes Summary
| Attribute |
Seamless |
Welded & Drawn |
Welded |
| Wall Tolerance |
 |
 |
|
| OD Tolerance |
|
|
 |
| Heavy Wall/OD |
|
|
|
| Cost |
|
|
|
| Grain Structure |
|
|
|
Process Conditions Evaluation
The selection of Welded, Welded & Drawn, or Seamless tubing and pipe would not be complete without evaluating process conditions for the leak risk. Consideration should be given to possible corrosion as well as to any potential hazards, as these factors will influence the selection of tubing type, the amount of non-destructive examination (NDE), and the need for corrosion evaluation.
Quality Tests Performed by RathGibson
| Test |
Type |
| Strength |
Tensile |
Destructive |
| Burst |
| Hardness |
Rockwell |
Destructive |
| Micro |
| Soundness |
Eddy Current |
NDE |
| Ultrasonic Testing |
| X-Ray |
| Leak & Strength |
Hydrostatic |
NDE |
| Leak |
Air Under Water |
NDE |
| Pressure Decay |
| Bend Testing |
Reverse Bend |
Destructive |
| Flattening |
| Reverse Flattening |
| Flange |
| Dimensional |
OD, Wall, Straightness |
NDE |
| Metallurgical |
Grain Size |
Destructive |
| Sensitization |
| Corrosion |
| Phase Balance or Intermetallic |
| Metallographic |
Sometimes, the selection process between Welded, Welded & Drawn, and Seamless can seem challenging. Based on a world class quality control program, RathGibson produces each product type to meet the most demanding quality, budgetary, and delivery needs. Trusting a respected and experienced manufacturer such as RathGibson is the first and best step in determining the ideal tubing and pipe to fit your specific quality requirements.
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