Specializing in instrumentation and process control components
SSP Tubes are synonymous with Safety and Convenience for instrumentation tubing applications. Instrumentation
tubing is designated according to its intended application, as well as by the type of mechanically attached fitting
selected to join the tubing.
Instrumentation tubing is generally described as thin-walled tubing with strict requirements to deviation in diameter
and wall thickness for leak-free operation on fluid transfer and pressure containment systems in process, oil & gas,
natural gas, power, cryogenic, and performance-critical OEM industries.
Purchasing tubing to ASTM, DIN or other equivalent specifications is a good start, additional requirements should
be considered. Most industry specification allow for rather wide variation in several important factors. Furthermore
these specifications don’t universally overlap thereby bringing into question the efficacy of tubing which is inside the
specification controls limits of one specification but not another.
So simply using an industry specification does not really mean that you have selected quality tubing.
Restricted Tolerance Controls
To be sure of selecting tubing whose quality is matched to the performance of precision-made instrument tube
fittings, SSP Tubes has restricted tolerance controls over the following variables important to the safe and reliable
operation of precision-manufactured instrument tube fittings.
- Material and Method of Manufacture - SSP Tubes are generally Dual Grade where possible. Dual Grade
means alloy with identical physical characteristics and only slightly different chemical characteristics are
specification- controlled favoring the grade with the more refined chemical characteristics.
- Hardness - All instrumentation tube fittings require that the tubing be softer than the fitting material. While
most metal tubing is restricted to a maximum hardness measured on the Rockwell hardness scale, SSP
Tubes have a lower restricted maximum hardness. This restricted tolerance control lowers installed cost by
allowing the tubing to be more easily bent and installed.
- Surface Finish - ASTM specifications are ambiguous on the subject of finishes. Instrumentation tubing
should be free from nicks, gouges, and deep scratches which can interfere with proper sealing, particularly in
gas service. SSP Tubes incorporate packaging and preservation standards which ensure that the tubing
arrives in proper condition for use in instrumentation systems.
- Roundness - ASTM A269 section 12.2 allows some thin-walled tubes to be produced with ovality of the tube
twice the OD tolerance of ±.005”. This degree of out-of-roundness would prevent the tubing from even
inserting into the tube fitting properly. SSP Tubes has restricted this tolerance to better control
- Dimensional - Wall Thickness & Outside Diameter Typical ASTM tubing specifications permit various
tolerances larger and smaller than the nominal OD rating (aka “plus” and “minus”). SSP Tubes has restricted
minimum tolerances on the “minus” because it is more difficult to seal undersized tubing reliably.
In addition to restricted tolerance control over important physical attributes of the tubing, SSP Tubes incorporate
several factors to increase the installer’s convenience and system performance when using SSP Tubes.
- Tube caps - Plastic protective caps are installed onto the end of each SSP Tube to preserve internal
cleanliness from the factory as well as to protect the end of the tube for maximum yield. Improperly protected
tube ends must be trimmed prior to using the tube. Tube caps prevent wasted time and material associated
with this practice.
- MAWP on lay line - SSP Tubes improve system safety and increase installer and operator confidence by
printing Maximum Allowable Working Pressure [MAWP] in psig and bar right onto the tube lay line. This
feature provides an additional measure of safety against using an inadequately rated tube in service. MAWP
are calculated using widely accepted ANSI /ASME B31.3 Process Piping specifications and code calculations.
- Fabrication - Virtually all tubes are prepared prior to installation. Preparation may involve:
- forming one or both ends by flaring or flanging the tube
- presetting or installing a tube nut, ferrule(s) or sleeve
- functional testing
- cleaning & packaging
SSP Tubes can be pre-fabricated by SSP to an end-user specification or a source control specification established
to ensure first-time quality in field service. Contact your local SSP product specialist for additional details on SSP
Inspection and Certification
SSP Tubes are fully heat and lot traceable. Chemical composition, yield, tensile strength, and elongation testing is
performed. SSP Tubes pass functional tests including flattening, flaring, dimensional, and leak testing via Eddy
current to ASTM A-450, as required. Finally, SSP Tubes are re-inspected using Energy-dispersive X-Ray
Fluorescence (EDXRF) technology.
Inspection certificates and summarized test results are issued with each tube of different size or lot. Certification is
always issued in compliance with EN 10 204 3.1 and ISO 10474.