Production Tubing: Sizes, Grades & Specifications Selection Guide
Production tubing is the steel string run inside the casing through which oil, gas and condensate flow to surface. It is an OCTG (Oil Country Tubular Goods) product manufactured to API 5CT, supplied in outside diameters from 1.050" up to 4-1/2", with 2-3/8", 2-7/8" and 3-1/2" covering the large majority of producing wells. Because tubing is the component fluids actually contact at flowing temperature and pressure, its grade and connection selection is driven as much by corrosion environment as by mechanical load — which is where most procurement errors happen.
ZC Steel Pipe (ZHENCHENG Steel Co., Ltd.) is a Chinese manufacturer of order-to-make OCTG, supplying production tubing across the full API 5CT grade range — from J55 and N80 sweet-service strings to L80, C90, T95 sour grades and L80-13Cr / Super 13Cr CO₂ grades — with NU, EU and gas-tight premium connections. This guide gives the dimensional tables, grade properties and selection logic engineers and procurement teams need to specify tubing correctly the first time.
CONTENTS
What Is Production Tubing?
Production Tubing vs Casing vs Line Pipe
API 5CT Tubing Sizes, Weights & Dimensions
Tubing Grades & Mechanical Properties
Tubing Connections: NU, EU, IJ & Premium
Sour & CO₂ Service Tubing Selection
How to Specify Production Tubing (PO Checklist)
Frequently Asked Questions
1. What Is Production Tubing?
Production tubing is the innermost, retrievable tubular string in a completed well. After the casing is cemented in place, tubing is run inside the production casing and landed on a packer, isolating the produced fluids from the casing-tubing annulus. Reservoir fluids travel up the tubing bore to the wellhead, so tubing must contain full reservoir pressure and resist whatever corrosive species (H₂S, CO₂, chlorides) the fluid carries.
DEFINITION — PRODUCTION TUBING (API 5CT)Tubing is OCTG run inside casing to convey produced or injected fluids. API 5CT covers tubing in OD labels from 1.050" to 4-1/2" in grades H40 through Q125. Unlike casing, tubing is designed to be retrieved and re-run, so connection sealing and make-up integrity are first-order design criteria, not afterthoughts.
Because tubing is replaceable, operators treat it as a consumable that may be pulled, inspected and re-run several times over field life. That changes the procurement priorities: connection galling resistance, sealability after multiple make-ups, and corrosion allowance matter more on tubing than on a casing string that is cemented once and forgotten.
2. Production Tubing vs Casing vs Line Pipe
All three are steel pipe, but they serve different jobs and follow different standards. Confusing them on a purchase order leads to wrong wall thickness, wrong connection, and rejected material at inspection.
Attribute | Production Tubing | Casing | Line Pipe |
Standard | API 5CT | API 5CT | API 5L |
Function | Carries fluid up the wellbore | Structural support of the hole | Transports fluid across distance |
OD range | 1.050" – 4-1/2" | 4-1/2" – 20"+ | 2-3/8" – 80"+ |
Retrievable? | Yes — pulled & re-run | No — cemented in place | No — buried/laid |
Typical grades | J55, N80, L80, T95, P110, 13Cr | K55, N80, L80, P110, Q125 | X42 – X80 (PSL1/PSL2) |
Key spec driver | Corrosion + connection seal | Collapse + burst | Yield + toughness (CVN) |
For a deeper breakdown of where the line-pipe / OCTG boundary sits, see Line Pipe vs OCTG — key differences →
3. API 5CT Tubing Sizes, Weights & Dimensions
The table below lists the common production tubing sizes from API 5CT 11th edition (Table C.19) for the most-ordered ODs. Weights are nominal; NU and EU columns reflect non-upset and external-upset configurations. Inside diameter and wall apply to the pipe body.
OD label | OD (mm) | Wall (mm) | ID (mm) | Nominal wt NU (lb/ft) | Nominal wt EU (lb/ft) | kg/m (NU) |
2-3/8" | 60.32 | 4.24 | 51.84 | 4.00 | — | 5.95 |
2-3/8" | 60.32 | 4.83 | 50.66 | 4.60 | 4.70 | 6.85 |
2-3/8" | 60.32 | 6.45 | 47.42 | 5.80 | 5.95 | 8.63 |
2-7/8" | 73.02 | 5.51 | 62.00 | 6.40 | 6.50 | 9.52 |
2-7/8" | 73.02 | 7.01 | 59.00 | 7.80 | 7.90 | 11.61 |
2-7/8" | 73.02 | 7.82 | 57.78 | 8.60 | 8.70 | 12.80 |
3-1/2" | 88.90 | 6.45 | 76.00 | 9.20 | 9.30 | 13.69 |
3-1/2" | 88.90 | 7.34 | 74.22 | 10.20 | — | 15.18 |
3-1/2" | 88.90 | 9.52 | 69.86 | 12.70 | 12.95 | 18.90 |
4" | 101.60 | 5.74 | 90.12 | 9.50 | — | 14.14 |
4" | 101.60 | 6.65 | 88.30 | 10.70 | 11.00 | — |
4-1/2" | 114.30 | 6.88 | 100.54 | 12.60 | 12.75 | 18.75 |
4-1/2" | 114.30 | 8.56 | 97.18 | 15.20 | — | 22.62 |
4-1/2" | 114.30 | 9.65 | 95.00 | 17.00 | — | 25.30 |
Source: API 5CT 11th edition, Table C.19. NU = non-upset, EU = external upset. Heavier walls available in each size; full table on request.
Procurement Note — Weight is a label, not the only number that matters. When a tally calls for "2-7/8 6.40#," that is the nominal weight tied to a specific wall (5.51 mm here). Two mills can both ship "6.40#" tubing that drifts differently if the upset geometry differs. If your completion runs tight-clearance tools, specify the required drift on the PO — do not assume it from the nominal weight.
For the casing string that tubing runs inside, our companion reference covers every OD: API 5CT casing sizes, dimensions & weight tables →
4. Tubing Grades & Mechanical Properties
API 5CT tubing grades span sweet-service carbon steels through controlled-hardness sour grades and chromium CO₂ grades. The table gives minimum and maximum specified yield, minimum tensile, and the controlling hardness cap where one applies.
Grade | Min yield (ksi / MPa) | Max yield (ksi / MPa) | Min tensile (ksi) | Max hardness | Service class |
J55 | 55 / 379 | 80 / 552 | 75 | — | General (sweet) |
N80-1 | 80 / 552 | 110 / 758 | 100 | — | General (sweet) |
N80Q | 80 / 552 | 110 / 758 | 100 | — | General (Q+T) |
L80-1 | 80 / 552 | 95 / 655 | 95 | 23.0 HRC | Sour service |
L80-13Cr | 80 / 552 | 95 / 655 | 95 | 23.0 HRC | CO₂ corrosion |
C90 | 90 / 621 | 105 / 724 | 100 | 25.4 HRC | Sour service |
T95 | 95 / 655 | 110 / 758 | 105 | 25.4 HRC | Sour service |
P110 | 110 / 758 | 140 / 965 | 125 | — | General (HPHT sweet) |
Source: api-5ct-spec.json (API 5CT 11th edition). HRC caps apply to the hardness-controlled grades. Yield values are specified minimum/maximum.
Engineering Insight — The tubing-grade decision tree Start with the environment, not the depth. (1) Any wet H₂S → controlled-hardness sour grade: L80-1, C90 or T95. (2) High CO₂ with no H₂S → 13Cr family (L80-13Cr / Super 13Cr). (3) Sweet, deep, high pressure → P110 for strength. (4) Shallow, low pressure → J55 or N80. Strength sizing comes after the metallurgy is fixed by the fluid.
For grade-by-grade context across the full OCTG range, see What are the grades of OCTG pipe → and How to choose OCTG material →
5. Tubing Connections: NU, EU, IJ & Premium
The connection is where most tubing failures and most procurement disputes occur. API 5CT defines three threaded-and-coupled tubing connection families, and the market adds proprietary premium threads on top.
NU (Non-Upset)
Designation: NU / NUE
Pipe end: Constant wall
Joint strength: ~ Reduced vs body
Best for: Shallow, low-load strings
EU (External Upset)
Designation: EU / EUE
Pipe end: Forged upset
Joint strength: ~ Pipe-body efficient
Best for: Deeper, higher-tension wells
IJ (Integral Joint)
Designation: IJ
Pipe end: Pin & box on body
Coupling: None (flush-ish)
Best for: Slimhole / clearance
Premium / Gas-Tight
Designation: Proprietary
Seal: Metal-to-metal
Gas tight: Yes
Best for: Sour / HPHT / gas
EUE is the workhorse for most producing strings because the external upset restores connection strength close to the pipe body. NUE is cheaper and lighter but trades away tensile efficiency. Where gas-tightness or sour-service sealing is required, an API thread is not enough — a metal-to-metal premium connection is the correct call.
Critical Engineering Point — API BTC/EUE threads are not gas-tight. Standard API threaded-and-coupled connections seal on thread compound, not metal-to-metal. For gas wells, sour service, or high-rate condensate, an API thread can leak at the connection even when the pipe body is sound. Do not specify EUE for a gas-tight duty and assume it will hold — move to a qualified premium connection.
Connection detail and selection economics are covered in EU & NU couplings explained → and Premium connections — usage & advantages →
6. Sour & CO₂ Service Tubing Selection
This is the single most expensive area to get wrong. The corrosive species in the produced fluid dictates the metallurgy, and two failure mechanisms — sulfide stress cracking from H₂S, and CO₂ (sweet) corrosion — require different solutions that are easy to confuse.
Critical — L80-13Cr is NOT a sour-service grade. L80-13Cr (and Super 13Cr) are CO₂ corrosion grades. They resist sweet CO₂ attack but are not qualified to NACE MR0175 / ISO 15156 for wet H₂S. Specifying 13Cr into a sour well because "it's corrosion-resistant" is a classic and dangerous substitution error. For H₂S, the qualified grades are L80-1, C90 and T95 — controlled-hardness carbon/low-alloy steels.
Dominant environment | Mechanism | Correct tubing grade | Avoid |
Wet H₂S (sour) | Sulfide stress cracking | L80-1 / C90 / T95 | N80, P110, 13Cr |
High CO₂ (sweet) | CO₂ corrosion / pitting | L80-13Cr / Super 13Cr | Bare carbon steel |
Sour + CO₂ combined | Both | Super 13Cr (NACE-qualified) or CRA | Standard 13Cr |
Sweet, deep, HPHT | Mechanical (pressure) | P110 | J55, N80 (under-rated) |
Sour determinations follow NACE MR0175 / ISO 15156. Always confirm partial-pressure thresholds against the actual well fluid analysis.
The metallurgy behind why 13Cr passivates against CO₂ but fails the sour hardness test is explained in L80-13Cr metallurgy & the Super gap → and the benefits of chrome tubing in 13 chrome tubing benefits →
7. How to Specify Production Tubing (PO Checklist)
A complete tubing purchase specification removes ambiguity and prevents rejected material at third-party inspection. Provide each of the following on the order:
Engineering Insight — Tubing PO must-haves
OD & nominal weight: e.g. 2-7/8" 6.40# — this fixes wall and ID.
Grade & type: e.g. L80 Type 1 (not just "L80") — type controls heat treatment and qualification.
Connection: NU / EU / IJ or named premium thread, with make-up torque spec.
Drift requirement: per API 5B, sized to your largest tool — tubing has no fixed drift in 5CT.
Service: sweet / sour (NACE MR0175) / CO₂ — triggers supplementary testing (SSC, hardness mapping).
Range & length: Range 2 (R2) is standard for tubing; confirm if R3 is required.
Inspection & certs: EMI/UT level, hydrostatic test, EN 10204 3.1/3.2 MTR.
Field Note — "L80" is not a complete grade. On a sour well, ordering "L80" without the Type 1 suffix invites the wrong material. L80-1 is the NACE sour grade; L80-9Cr and L80-13Cr are CO₂ grades that share the "L80" yield band but are not interchangeable for H₂S. Always write the full type designation on the tally and the PO.
ZC manufactures to order, so non-standard wall, length and premium-connection combinations can be quoted directly against your completion design rather than forced into stock sizes. View the full casing & tubing product range → or, for thermal / slimhole strings, our coiled tubing →
8. Frequently Asked Questions
What is production tubing in oil and gas?
Production tubing is the innermost steel string run inside the casing through which oil or gas flows to surface. It is an OCTG product manufactured to API 5CT in outside diameters from 1.050" to 4-1/2", with 2-3/8", 2-7/8" and 3-1/2" being the most common production sizes.
What is the difference between tubing and casing?
Casing is the structural string cemented into the wellbore to support the hole; tubing is the smaller-diameter, retrievable string run inside the production casing to carry produced fluids. Both follow API 5CT, but tubing maxes out at 4-1/2" OD while casing runs from 4-1/2" up to 20" and larger.
What is the difference between EUE and NUE tubing?
NUE (non-upset, designated NU) keeps a constant pipe-body wall and threads directly into a coupling, giving a thinner joint with lower tensile efficiency. EUE (external upset, designated EU) forges a thicker upset on each pipe end before threading, restoring near pipe-body strength at the connection. EU is preferred for deeper strings and higher loads.
Which tubing grades are suitable for sour (H2S) service?
API 5CT grades L80 Type 1, C90 and T95 are qualified for sour service under NACE MR0175 / ISO 15156 because of their controlled hardness. L80-13Cr is a CO₂ corrosion grade only and is not a NACE sour-service grade, while N80 and P110 are general-service grades not intended for wet H₂S exposure.
What sizes does production tubing come in?
Common API 5CT production tubing outside diameters are 2-3/8" (60.32 mm), 2-7/8" (73.02 mm), 3-1/2" (88.9 mm), 4" (101.6 mm) and 4-1/2" (114.3 mm). Nominal weights range from about 4.0 lb/ft on 2-3/8" up to 26.1 lb/ft on heavy-wall 4-1/2".
Does production tubing have a drift diameter?
Tubing does not carry a single fixed drift in API 5CT the way casing does. The drift diameter for tubing is specified on the purchase order per API 5B, sized to the largest tool or pump string the operator needs to pass. Always confirm the required drift before ordering.
Source Production Tubing from ZC Steel Pipe
ZHENCHENG Steel Co., Ltd. (ZC Steel Pipe) manufactures order-to-make API 5CT production tubing across the full grade range — J55, N80, L80 (sour Type 1 and 13Cr CO₂), C90, T95 and P110 — with NU, EU, IJ and gas-tight premium connections. Projects delivered across Africa, the Middle East and South America, with independent patents in premium connections and special-grade OCTG.
Email: mandy.w@zcsteelpipe.com | WhatsApp: +86-139-1579-1813
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Related: API 5CT Casing Sizes & Weights · OCTG Grades · EU & NU Connections · 13Cr Tubing · Casing & Tubing Product Page
