Masoneilan 28000 HP High Pressure Varipak Microflow Control Valve

Overview

The Masoneilan 28000 HP is the high-pressure body of the Baker Hughes Varipak microflow control valve. It is built for services where the upstream pressure, or the pressure drop across the valve, is higher than the standard Varipak body can be rated for. Where a standard Varipak is limited to ASME Class 1500, the 28000 HP Series carries an ASME Class 2500 (ISO PN 420) rating in the 1 inch (DN 25) size, with rated Cv from 0.60 down to 0.0040 across trim numbers 3 to 9.

In Oman and the GCC, Seven Star LLC proudly supplies the Masoneilan 28000 HP to oil and gas, chemical and research customers across the Sultanate of Oman and the GCC. Our valve team in Muscat reviews the maximum pressure, temperature and fluid before recommending the trim number and checking that the packing and bolting listed for Class 2500 suit the service.

What Class 2500 Changes in a Microflow Valve

A microflow valve such as the Masoneilan 28000 HP is physically small, so a Class 2500 rating is achieved through wall thickness, material and sealing rather than size. The Masoneilan 28000 HP keeps the compact Varipak footprint: the 1 inch flangeless or threaded body is still 4.02 inches (102 mm) face to face, and the high-pressure dimensional drawing carries the same 10.24 inch (260 mm) and 12.80 inch (325 mm) overall figures as the standard valve. The differences are inside the pressure boundary. The Class 2500 body is forged from ASTM A182 F316 or F316L, or ASTM A479 type 316 or 316L for printed flanged bodies, and the packing flange studs change to ASTM B637 grade 718, an age-hardened nickel alloy.

The sealing system of the Masoneilan 28000 HP is also different. For Class 2500 the packing set is braided PTFE of the Lattyflon 3260 LM type, and an anti-extrusion ring of exfoliated graphite, James Walker Supagraf Control, is added; Baker Hughes marks both as parts for which no equivalents are allowed. These are the details that keep a stem seal tight at very high pressure, and they are the reason a Class 2500 valve should be ordered as an HP construction rather than created by uprating a standard body. The safety pin of the standard body is listed as not applicable for Class 2500.

Engineering Design of the Masoneilan 28000 HP

The Masoneilan 28000 HP shares the Varipak trim platform, with trim numbers 3 to 9 available in the high-pressure design for a nominal Cv from 0.0016 to 0.60: trim 3 gives 0.25 to 0.60, trim 4 gives 0.10 to 0.25, trim 5 gives 0.04 to 0.10, trim 6 gives 0.020 to 0.050, trim 7 gives 0.010 to 0.025, trim 8 gives 0.004 to 0.010 and trim 9 gives 0.0016 to 0.0040. The critical flow factor is 0.90 for trims 3 and 4 and 0.85 for trims 5 to 9, and flow is to open. For the smallest trims 6 to 9 the seat ring and spacer are Stellite No. 6 or equivalent and the plug is cast solid in Stellite No. 12.

Temperature capability of the Masoneilan 28000 HP follows the stainless steel construction: -50°F to +650°F (-46°C to +343°C), or -20°F to +450°F (-29°C to +232°C) with NACE materials. Seat leakage is Class IV as standard. The connection to the process is by flangeless or threaded body for the 1 inch size, and the actuator is the spring-opposed rolling diaphragm design of the Varipak family, with direct or reverse action, an optional top-mounted handwheel and an optional Cv adjustment knob. Supply and instrument connections are 1/4 inch NPT on the high-pressure dimensional drawing.

Key Features

The following points summarise what the Masoneilan 28000 HP offers over a standard Varipak:

• ASME Class 2500 and ISO PN 420 pressure rating in a compact 1 inch (DN 25) microflow valve.
• Rated Cv range of 0.60 to 0.0040 through trim numbers 3 to 9 for very low flow control at high pressure.
• Forged or bar-stock 316 and 316L stainless steel body for the high-pressure boundary.
• Packing flange studs in age-hardened ASTM B637 grade 718 alloy.
• Lattyflon braided PTFE packing with a Supagraf Control exfoliated graphite anti-extrusion ring, specified without equivalents.
• Class IV seat leakage and flow-to-open action with a Cv ratio of 500:1 at maximum Cv.
• Same overall drawing figures and 5.5 inch (140 mm) removal clearance as the standard Varipak.
• NACE material option for sour service up to +450°F.

Industrial Applications

The Masoneilan 28000 HP is intended for typical high-pressure sampling and injection lines, hydraulic and test-rig control, high-pressure gas letdown to instruments, and high-pressure chemical injection into pipelines or wells. In Oman, such services can arise in upstream oil and gas facilities, gas compression stations and the test laboratories attached to refineries and power plants, where an instrument-scale valve must still withstand the full line pressure.

Seven Star LLC, the trusted supplier for Masoneilan, distributes the Masoneilan 28000 HP across Oman and the GCC, including projects in the Sohar and Salalah economic zones. Where the pressure stays within Class 1500, the standard Masoneilan 28000 Series Varipak valve is normally sufficient; the 28000 Varipak seal and O-ring kit covers maintenance spares, and the Masoneilan SVI3 digital valve positioner is one of the digital positioner types the Varipak documentation lists.

Technical Specifications

The table gathers the high-pressure data that the Baker Hughes Varipak technical specification (Rev. C, 12/2025) publishes for the Masoneilan 28000 HP. Complete dimensions and the full materials list remain in the official document.

Request a Quote for Masoneilan 28000 HP

A formal RFQ for the Masoneilan 28000 HP should state the maximum pressure, temperature, fluid and required Cv, which lets our Muscat instrumentation division confirm the trim number and the Class 2500 sealing materials and check regional stock. The Baker Hughes technical specification is available for download from this page. Seven Star LLC is the trusted supplier for Masoneilan in Oman and the GCC and backs every valve with genuine documentation, factory warranty and local support.