API 5CT C95 Oilfield Casing Pipe

API 5CT C95 is a high-strength oilfield casing grade that appears in older API 5CT specifications and related industry references. Its minimum yield strength is 95 ksi (655 MPa), higher than the 80 ksi minimum of N80.

There is an important point for buyers today: C95 is not listed among the grades covered by the current API 5CT 11th Edition. The current specification covers grades including C90, R95, T95, P110, C110, C125 and Q125, but not C95.

That does not necessarily make an older C95 purchase requirement unusable. C95 can still appear in legacy project specifications, replacement orders, or customer specifications based on an earlier edition of API 5CT.

If your RFQ calls for C95, the safest approach is to confirm the applicable API 5CT edition or project specification before ordering. The casing size, weight or wall thickness, length range, connection, inspection requirements, and documentation should also be stated clearly.

API 5CT C95 Specifications

Here's a quick‑reference table of the key specification parameters. Save this for your procurement documents.

Chemical Composition of API 5CT C95 Grade

The chemical composition of C95 is what gives it the strength and toughness profile that drilling operations demand. The spec controls key elements tightly - especially phosphorus and sulfur, which are kept very low to reduce brittleness and cracking risk.

A couple of things worth pointing out: Molybdenum has both a minimum (0.25%) and maximum (0.85%) limit - that's because Mo plays a critical role in achieving the right hardenability for Q&T processing. Too little and you won't get the strength; too much and you risk brittleness. The sulfur limit of 0.010% is quite tight, which is characteristic of Group 2 controlled grades.

Pro tip for buyers: Always request the Mill Test Certificate (MTC) per EN 10204 Type 3.1 for every heat. Verify that the actual chemistry falls within these limits - don't just take the supplier's word for it.

Mechanical Properties of API 5CT C95

The mechanical properties are where C95 really defines itself. These values are non‑negotiable - if the pipe doesn't meet them, it doesn't meet the spec. Here's the full breakdown:

One correction is worth making here because C95 is often confused with C90 and T95.

C95 does not have the 25.4 HRC maximum hardness requirement shown for C90 and T95 in API 5CT tables. Historical data lists C90 and T95 with a 25.4 HRC maximum, while C95 has no corresponding hardness limit in that table.

So a C95 product page should not present 25.4 HRC as a C95 specification requirement unless a separate project specification requires it.

Allowable Hardness Variation by Wall Thickness

API 5CT also specifies how much hardness can vary across the pipe wall, depending on wall thickness. This matters because thicker walls are harder to quench uniformly.

C95 Casing Pipe Sizes and Dimensions

Casing size is selected as part of the well design. OD, wall thickness, nominal weight, connection, collapse resistance, burst performance, and installation requirements all need to be considered together.

Common API casing outside diameters include:

The OD alone is not enough to identify a casing product. The buyer should also specify the nominal weight or wall thickness, connection, and length range.

C95 Casing Lengths

API casing is commonly ordered by length range:

The required range should be stated in the RFQ because length affects the number of joints, shipping quantity, and well planning.

For example, a buyer may specify:

C95 casing, 7", specified weight, BTC, R3, 300 joints.

The final length requirements should be checked against the applicable specification and purchase order.

C95 Casing Thread Connections

For casing, the connection should be specified separately from the steel grade.

Common API casing connections include:

STC - Short Round Thread Casing

STC is a short-round-thread casing connection. It is used for casing applications where the connection's mechanical and sealing performance meets the well design requirements.

LTC - Long Round Thread Casing

LTC, commonly referred to as LC in API terminology, has a longer round thread than STC.

BTC - Buttress Thread Casing

BTC, commonly referred to as BC in API terminology, uses a buttress thread profile and is widely used for casing applications where the connection needs greater axial load capacity than round-thread connections.

The connection should not be chosen from the grade alone. Casing design loads, pressure, well conditions, make-up requirements, and sealing performance all matter.

If a project calls for a premium connection, the exact connection name and applicable qualification requirements should be included in the RFQ.

C95 vs Other API 5CT Grades - How It Compares

One of the most common questions we get is: "Should I use C95 or [another grade]?" The answer depends on your well conditions - depth, pressure, temperature, and fluid composition. Here's a head‑to‑head comparison to help you decide:

Key takeaway: C95 shares the same yield/tensile/hardness profile as C90, but without the sour service qualification. If you need the same strength and H₂S resistance, go with C90 or T95. If you need higher strength without sour service, R95 or P110 might be your pick.

Color Code Identification

API 5CT uses a color‑coding system to help identify pipe grades on the rig site. For C95, the identification is straightforward:

Always verify the grade by checking both the color code and the stenciled markings on the pipe. The marking should include the manufacturer's name, standard, grade, OD, wall thickness, length, and heat number.

API 5CT C95 casing and tubing

API 5CT C95 OCTG Steel Pipe

API 5CT C95 Casing Pipe

API 5CT C95 Petroleum Steel Pipe

Applications of API 5CT C95 Casing Pipe

C95 casing pipe is used across a range of oilfield applications, primarily where you need higher strength than standard grades but don't necessarily need the full sour service qualification of C90 or T95. Typical use cases include:

• Intermediate and production casing strings in medium to deep wells where formation pressures require yield strength above 80 ksi
• Surface casing in deeper well designs that need extra structural integrity
• Wells with mildly corrosive environments where the hardness control of C95 provides a safety margin, but full H₂S sour service qualification isn't required
• Oil and gas transportation from the producing zone to the surface pipeline after drilling is completed
• Wellbore wall support - preventing collapse of the borehole and protecting the tubing pipe

That said, if your well environment contains significant H₂S (hydrogen sulfide), you should not be using C95. In that case, specify C90, T95, or C110 - those are the NACE MR0175/ISO 15156‑2 approved sour service grades.

Manufacturing Process

C95 casing pipe is manufactured using two primary methods:

Seamless Pipe (SML)

The go‑to method for high‑grade casing. Seamless pipe is produced by rotary piercing or continuous mandrel rolling, where a solid steel billet is heated and pierced to form a hollow tube without any weld seam. This eliminates the weld as a potential failure point - which is exactly what you want in high‑pressure downhole environments. Most C95 casing on the market is seamless.

Electric Resistance Welded (ERW)

ERW pipe is formed by rolling steel plate into a cylinder and welding the seam using electrical resistance. While ERW has improved significantly over the years and can meet API 5CT requirements, it's generally used for less critical applications or when cost is a primary driver. For C95 specifically, seamless is the preferred and more common choice.

Heat Treatment

As a Group 2 grade, C95 requires Quenched and Tempered (Q&T) heat treatment. The pipe is heated to austenitizing temperature, rapidly quenched (typically in water or polymer), and then tempered at a lower temperature to achieve the right balance of strength, toughness, and hardness. This process is what gives C95 its controlled mechanical properties - without proper Q&T, the pipe won't meet spec.

Looking for cut‑to‑length C95 casing pipe? We offer custom cutting, threading, and coupling services to match your exact well specifications. Get a Custom Quote →

C95 Casing Inspection and Testing

Inspection should be based on the applicable specification, purchase order, and agreed inspection plan.

Depending on the order, inspection may include:

Chemical Analysis

The heat chemistry is checked against the specified material requirements and recorded on the MTC.

Tensile Testing

Tensile testing verifies the required yield strength, tensile strength, and elongation.

Hydrostatic Testing

Hydrostatic testing is performed according to the applicable specification and purchase requirements.

The test pressure should not be presented as one fixed value for every C95 casing size. Historical API/ISO tables show that hydrostatic test pressure varies with casing size, weight, and connection.

Drift Testing

A drift test checks whether the casing maintains the required internal diameter over its length.

NDE

Depending on the specification, manufacturing route, and purchase order, non-destructive examination may include ultrasonic, electromagnetic, or other specified methods.

Dimensional Inspection

Typical dimensional checks include:

Outside diameter

Wall thickness

Length

Weight

Straightness

End dimensions

Thread dimensions

Coupling dimensions

Thread Inspection

Thread inspection is especially important for casing because thread damage or dimensional errors can affect make-up and connection performance.

For critical orders, third-party inspection can be arranged when required by the buyer.

FAQ

Is API 5CT C95 a sour service grade?

No. C95 is not classified as a sour service grade and is not listed in NACE MR0175/ISO 15156‑2 as an approved grade for H₂S‑containing environments. While C95 does have a maximum hardness limit of 25.4 HRC (which provides some resistance to sulfide stress cracking), it does not carry the full sour service qualification that C90, T95, or C110 have. If your well contains H₂S, use one of those grades instead.

Was C95 removed from the API 5CT standard?

Yes. C95 was removed from API Spec 5CT starting with the 9th Edition (2011). It was replaced by R95, which has a higher yield strength range (655–758 MPa) but without mandatory hardness testing. The current 11th Edition (2023) does not include C95. However, many manufacturers still produce C95 pipe to earlier edition specifications, and it remains widely available in the market.

What is the difference between C95 and R95?

The main differences are: (1) R95 has a higher yield strength range (655–758 MPa vs. 621–724 MPa for C95); (2) R95 does not have mandatory hardness requirements, while C95 has a maximum hardness of 25.4 HRC / 255 HBW; (3) R95 is in the current API 5CT standard, while C95 is not. If you need hardness control, C95 is the better choice. If you need higher yield strength without hardness testing, R95 is the way to go.

What is the difference between C95 and C90?

C95 and C90 have identical mechanical properties (yield strength, tensile strength, and hardness limits). The key difference is that C90 is a dedicated sour service grade with stricter chemical composition controls and NACE MR0175/ISO 15156‑2 compliance, available in two types (Type 1 and Type 2 with different chemistries). C95 has less restrictive chemistry and is not sour service qualified.

What is the difference between C95 and T95?

T95 has a higher yield strength range (655–758 MPa vs. 621–724 MPa for C95) and higher minimum tensile strength (724 MPa vs. 689 MPa). T95 is also a NACE‑approved sour service grade, while C95 is not. Both share the same maximum hardness limit of 25.4 HRC / 255 HBW. For deep wells with H₂S, T95 is the correct choice.

What sizes are available for C95 casing pipe?

C95 casing pipe is available in outer diameters from 4‑1/2" (114.3 mm) to 20" (508 mm), with various wall thicknesses depending on the size. Common sizes include 5‑1/2", 7", 9‑5/8", and 13‑3/8". Length ranges follow API standards: R1 (4.88–7.62 m), R2 (7.62–10.36 m), and R3 (10.36–14.63 m).

What thread types are available for C95 casing?

C95 casing is available with STC (Short Round Thread Casing), LTC (Long Round Thread Casing), and BTC (Buttress Thread Casing) connections. For tubing sizes, EUE (External Upset End), NUE (Non‑Upset End), and IJ (Integral Joint) connections are available. Premium connections with metal‑to‑metal seals can also be supplied for critical applications.

What is the color code for C95?

C95 is identified by one brown band on the pipe body and a solid brown coupling with no additional band color.

Can C95 casing pipe be welded?

C95 is primarily manufactured as seamless pipe, but ERW (Electric Resistance Welded) versions are also available. Field welding of casing is generally not recommended for high‑strength grades - threaded connections (STC, LTC, BTC) are the standard joining method. If welding is absolutely necessary, it must be performed by qualified personnel using approved procedures with proper pre‑heat and post‑weld heat treatment.

What heat treatment does C95 receive?

C95 is Quenched and Tempered (Q&T). The pipe is austenitized, rapidly quenched, and then tempered to achieve the specified combination of strength, toughness, and hardness. This is consistent with all Group 2 grades in API 5CT, which require controlled heat treatment to meet their mechanical property requirements.

What documentation should I request with my C95 order?

At minimum, request: (1) Mill Test Certificate per EN 10204 Type 3.1 (or 3.2 for third‑party witnessed); (2) Material Test Report with full chemistry and mechanical test results for each heat; (3) NDE/inspection reports; (4) Dimensional inspection records; (5) Heat number traceability. For sour or critical service applications, also request NACE compliance documentation if applicable.

What is the typical delivery time for C95 casing pipe?

For ex‑stock material, delivery is typically 7–25 days after receiving the deposit. For new production orders, expect 30–60 days depending on quantity, size, and threading requirements. Always confirm lead times with your supplier before placing the order, especially for large quantities or non‑standard sizes.

Get Your C95 Casing Pipe Quote Today

Whether you need a single truckload or a full well program's worth of C95 casing pipe, we've got you covered. Here's what we offer:

• Full size range: 4‑1/2" to 20" OD, seamless and ERW
• All thread types: STC, LTC, BTC, EUE, NUE, IJ, and premium connections
• Custom processing: Cut‑to‑length, threading, coupling, coating, drifting
• Complete documentation: EN 10204 3.1/3.2 MTC, full traceability
• Third‑party inspection: SGS, BV, TÜV welcome
• Global shipping: Bundle packaging with thread protectors

Request Your Quote Now

Disclaimer: This article is for informational purposes only. Always consult the current edition of API Spec 5CT and applicable standards (NACE MR0175/ISO 15156‑2) for your specific application. C95 has been removed from API Spec 5CT since the 9th Edition; verify grade availability and specification compliance with your supplier before ordering.

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