What is a barred tee and why is it used in pipelines?

A barred tee is a standard tee fitting with steel bars welded across the branch opening. The bars guide a pipeline inspection or cleaning tool (called a PIG — Pipeline Inspection Gauge) through the main run of the tee without allowing the pig to enter the branch. This is essential in piggable pipeline systems where the main line must remain clear for pig passage while branch connections (to measurement stations, valves, or dead-legs) are blocked to the pig. Without bars, the pig could enter the branch, become stuck, and require costly retrieval operations.

What is WPHY 65 and how does it differ from WPHY 60?

WPHY 65 and WPHY 60 are both high-yield strength ferritic steel fitting materials per ASTM A860. The number refers to the minimum specified yield strength: WPHY 60 has minimum yield strength of 60 ksi (414 MPa) and WPHY 65 has minimum yield strength of 65 ksi (448 MPa). Both are significantly stronger than standard ASTM A234 WPB fittings (35 ksi yield). WPHY 65 is preferred for higher-pressure offshore pipelines and is the more common specification in Indian SPM and PLEM projects. WPHY 60 may be specified where lower SMYS is matched to the pipeline wall thickness and design pressure.

What is the typical lead time for WPHY 65 barred tees for an offshore project?

WPHY 65 barred tees for offshore SPM/PLEM projects are specialty items. Lead time depends on size, wall thickness, NACE requirement, and whether heat-specific material is available. For sizes up to 24-inch, allow 12–18 weeks for forged or extruded tee with bar fabrication, NACE-compliant heat treatment, NDE, and coating. For sizes 30-inch and above, 18–26 weeks is typical. For critical-path procurement, provide drawings and project datasheet as early as possible to allow material reservation and heat number traceability planning.

Barred Tee and Piggable Tee — WPHY 65, ASTM A860, Offshore Pipeline Supply

Technical guide · Supreme Valves India · 2026

What is a Barred Tee?

A barred tee is a tee pipe fitting — either seamless extruded, fabricated, or forged — in which steel bars (or a bar grid) are welded across the inside of the branch opening. The function of these bars is to guide a pipeline inspection or cleaning tool — known as a PIG (Pipeline Inspection Gauge, or Pipeline Inspection and Cleaning tool) — through the main run of the tee without allowing the pig to deviate into the branch pipe.

In a conventional tee without bars, a pig travelling along the main pipeline will be deflected into the branch opening rather than continuing straight through the run. For piggable pipeline systems — where smart pigs, foam pigs, or disc/cup cleaning pigs are regularly launched and received — this deflection would trap the pig in the branch, require shutdown, and potentially require branch pipe removal to retrieve the tool. The barred tee eliminates this risk by providing a physical guide that bridges the branch opening and keeps the pig on the main run trajectory.

When Barred Tees are Required

Barred tees are required wherever a branch connection exists on a piggable pipeline — any pipeline that is designed for pig passage for inspection, cleaning, or batching. Key applications include:

SPM (Single Point Mooring) pipelines: Crude oil transfer pipelines from shore tank farm to the mooring point in the sea — regularly pigged for wax/scale cleaning and internal corrosion inspection
PLEM (Pipeline End Manifold): The subsea manifold termination of the SPM hose system — valved connections to multiple flowlines require barred tees on the main pig run
Subsea and offshore pipelines: Gas and crude export lines from offshore platforms — pig traps at platform end, ILI (in-line inspection) runs require all branch connections to be barred
Onshore cross-country pipelines: OISD-STD-141 (Indian PNGRB regulations) mandate pig-compatible fittings including barred tees on all piggable trunk lines

WPHY 65 Material — ASTM A860

ASTM A860 is the standard specification for wrought high-strength ferritic steel butt-welding fittings for low-temperature service in offshore and pipeline applications. Grade WPHY 65 within this standard specifies:

Minimum yield strength: 65 ksi (448 MPa)
Minimum tensile strength: 535 MPa
Maximum hardness: 22 HRC per NACE MR0175 (for sour service applications)
Chemical composition: Carbon-manganese steel with micro-alloying additions (Nb, V, Ti) for yield strength without excessive carbon equivalent
Heat treatment: Normalised (N), normalised and tempered (NT), or quenched and tempered (QT) — project specification will state which is required
Charpy impact testing: Required at low temperature (typically –20°C or –46°C for offshore) to ensure adequate toughness

WPHY 65 is the standard pipeline fitting material for SPM and PLEM projects in India handled by EIL, ONGC, HPCL, and MRPL. It matches the API 5L X65 line pipe material typically used for these pipelines, ensuring compatibility of carbon equivalent and weldability.

Barred vs Unbarred Tee — Selection Criteria

The decision to use a barred vs unbarred tee depends on the pig type being used and the pigging design philosophy:

Foam and brush pigs: Flexible enough to negotiate some branch entries; however, PNGMB and offshore codes still require barred tees on any branch >30% of the run pipe ID
Disc and cup pigs: Rigid geometry — will always enter a branch if not barred; barred tees mandatory
Intelligent (smart) pigs (MFL, UT): Complex tool geometry and electronics; barred tees essential to prevent tool damage and loss
Non-piggable pipelines: Unbarred tees acceptable on lines that will never be pigged — confirm with project pigging philosophy document before specifying

Bar spacing inside the branch must be sized to prevent pig entry — typically bars are spaced at a clear gap less than 1/3 of the pig minimum OD. Project pigging specification will state the bar spacing requirement.

Construction Details

WPHY 65 barred tees for offshore service are typically constructed as:

Body: Extruded tee per ASME B16.9 or MSS SP-75 from WPHY 65 material, or fabricated from seamless pipe with branch stub welded in; for large diameter (>24"), fabricated from heavy-wall plate is common
Bar fabrication: Flat or round bars of equivalent WPHY 65 or carbon steel (API 5L X60/X65) welded across the branch opening at the tee crotch; bar-to-bore clearance is confirmed by QC inspection before final inspection
Weld procedure: WPQR per ASME IX or EN ISO 15614; preheat and PWHT per project specification (typically above 200°C for WPHY 65 where CE >0.42)
NDE: RT or UT of all circumferential butt welds, MT of all fillet and branch welds, dimensional inspection per ASME B16.9 / MSS SP-75
Coating: External FBE (Fusion-Bonded Epoxy) to holiday-tested 300–400 µm DFT; field joints wrapped with heat-shrink sleeve or cold-applied tape at installation

Pressure Classes for Offshore

SPM and PLEM fittings are typically rated per ASME B16.5 / ASME B16.47 pressure classes or matched to the pipeline design pressure:

Class 300 (PN50): Common for lower-pressure crude oil transfer lines (design pressure ~50 bar)
Class 600 (PN100): Used for higher-pressure gas export or HIPPS-rated lines (design pressure ~100 bar)
Class 900 and above: Subsea flowlines, high-pressure gas injection — specialty items with extended lead time

SPM Application Context

A typical SPM project for HPCL Vizag or MRPL Mangalore involves a 20"–24" mainline running from the shore tank farm manifold through a marine spread (submarine pipeline + surface flexible hoses) to a Catenary Anchor Leg Mooring (CALM) buoy. The shore manifold area incorporates multiple barred tees connecting the mainline to individual tank farm feeds and measurement stations. All tees on the piggable main run are barred; tees on isolation/block valve bypasses that are not part of the pig run may be unbarred.

Supreme Valves India procures and supplies WPHY 65 barred tees for Indian offshore EPC projects with full traceability documentation including heat certificates, hydrotest records, NDE reports, dimensional reports, and coating holiday test results.

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