Instrument tubing is judged on three things a pipe standard barely mentions: how soft it is, how round it is and how clean its surface is, because a compression ferrule has to bite into that surface and seal against it. Chemistry is the easy part of this order. Our stainless steel instrumentation tubing is supplied fully annealed to ASTM A269 in 316 and 304, in fractional and metric sizes. Tolerances and surface condition are held to what compression fittings need. It runs impulse, analyser and control lines at plants across Oman. Other stainless products are on the stainless steel pipes and tubes hub.
Where Instrumentation Tubing Is Used
- Impulse lines to pressure, level and flow transmitters
- Analyser and sample lines, including heat-traced bundles
- Pneumatic supply and signal lines to valve positioners and actuators
- Hydraulic control lines on valves and wellhead equipment
- Chemical injection and small-bore dosing lines
Grades Supplied
SS 316 Instrumentation Tubing
The default choice for outdoor, coastal and offshore installations, where molybdenum resists the chloride attack that pits 304. Usually supplied dual certified 316/316L. See SS 316 instrumentation tubing.
SS 304 Instrumentation Tubing
An economical choice for indoor and sheltered service, such as control room panels and dry plant areas. Not suitable for coastal exposure. See SS 304 instrumentation tubing.
For severe chloride or sour conditions, higher alloys such as 254 SMO or duplex are specified instead.
What Makes Tube "Instrumentation Grade"
Requirement | Why it matters | What to state on the order |
|---|---|---|
Fully annealed condition | The ferrule must bite into the tube wall to seal | Annealed, with hardness limit |
Hardness | Fitting makers commonly require 80 HRB maximum for 316 | The hardness limit your fitting system specifies |
OD tolerance and ovality | The seal is made on the outside surface | Tolerance class or the fitting maker's requirement |
Surface condition | A longitudinal scratch under the ferrule is a leak path | Bright annealed or pickled, free of defects |
Wall consistency | Affects pressure rating and bending | Wall and tolerance |
Cleanliness | Debris inside impulse lines blocks or contaminates readings | Capped ends, degreased where specified |
Ordering plain "316 tube" against a general tube standard can bring material that is harder or wider in tolerance than compression fittings accept, which is the most common cause of leaking tube joints on commissioning.
Standards and Sour Service
ASTM A269 is the usual standard, often with supplementary requirements for hardness, tolerance and surface. Fitting manufacturers publish their own tube requirements, which typically go beyond the ASTM minimums. Under NACE MR0175 / ISO 15156-3, 316L is accepted for sour service within defined limits, and higher alloys are used beyond them. State your service conditions in the RFQ; requirements are confirmed at quotation.
Price Factors
- Grade (316 costs more than 304, and both follow nickel and molybdenum markets)
- OD, wall and total length
- Straight lengths or coils
- Hardness, tolerance and surface requirements
- Cleaning, degreasing and capping
- Quantity and stock availability versus a mill order
- Certification (EN 10204 3.1 or 3.2) and third-party inspection
- Incoterm and destination port
Quotations are available in USD, OMR, AED, SAR, QAR, KWD and BHD, on EXW, FOB, CFR or CIF terms.
What to send for a quotation:
grade, OD, wall, size system, straight or coil, length, quantity, fitting system, hardness and surface requirements, certification, inspection, destination port and required date.
Certificates and Inspection
Instrumentation tubing is supplied with EN 10204 3.1 certificates as standard, and EN 10204 3.2 certificates on request. Inspection by the buyer's nominated third-party agency can be arranged; state your requirement in the RFQ. Check that hardness is reported, not just chemistry and tensile results, since hardness is the property the fittings depend on. See the MTC and EN 10204 certification guide.
Packing and Storage
Lead time is confirmed at quotation. Tubing ships capped and wrapped, often in wooden crates, since a scratched or dented surface cannot be repaired in the sealing area. Store it indoors, away from carbon steel and grinding dust, and keep the caps on until the run is being installed.
Related Products
- SS 316 instrumentation tubing
- SS 304 instrumentation tubing
- Stainless steel fittings and flanges hub
- Stainless steel seamless pipes and tubes
Instrumentation tubing is used across oil and gas, refinery and petrochemical, marine and offshore and desalination and water treatment installations.
Instrumentation Tubing FAQ
What makes instrumentation tubing different from ordinary tube?
It is fully annealed with close OD tolerance and a clean surface, so compression ferrules can bite and seal. A general tube standard alone does not guarantee those properties.
What hardness is required?
Fitting manufacturers commonly specify 80 HRB maximum for 316 tubing. Confirm the limit for the fitting system you use.
Should I use 316 or 304?
316 for outdoor, coastal and offshore installations; 304 only indoors in dry, chloride-free conditions.
Can metric and fractional tubing be mixed?
No. A 12 mm tube will not seal in a 1/2 inch fitting. Standardise on one system across the plant.
Which standard covers instrument tubing?
ASTM A269, usually with supplementary hardness, tolerance and surface requirements.
What should I send for a quotation?
Send the grade, OD, wall, size system, length, quantity, fitting system, hardness and surface requirements, certification and destination port.
Request a Quote for Instrumentation Tubing
Send the grade, size system, OD, wall and quantity, with the fitting system named. Every enquiry is checked before the offer is prepared, so hardness, tolerance and surface requirements match the fittings rather than only the standard.