FITOK NUSS-FNS2-7 Union Bonnet Needle Valve, 1/8 in. NPT

NUSS-FNS2-7 is a FITOK NU Series union bonnet needle valve in 316 stainless steel with 1/8 in. female NPT ends. The product page lists 6,000 psig (414 bar), a range of -65 F to 450 F (-54 C to 232 C), a 0.16 in. orifice and Cv 0.35.

High pressure in a very small needle valve

This is the smallest thread size in the NU catalog and it carries the highest pressure rating of the examples in this lane. A 1/8 in. NPT connection keeps weight and volume low, so the valve suits dead-end instrument lines where a bulky valve would load the tubing.

Union bonnet means the bonnet is attached by a large nut. Releasing the nut allows the stem assembly to be removed for repacking or seat replacement without unscrewing the body from the line, which an integral bonnet valve does not allow. In the code, NU is the series, SS is the 316 stainless steel body, FNS2 is the 1/8 in. female NPT and 7 is the orifice code.

Catalog features

• Union bonnet design with a body that can stay in the line during maintenance.
• 6,000 psig (414 bar) at -65 F to 450 F (-54 C to 232 C).
• Packing choice: PEEK packing extends the limit to 500 F and graphite to 1,200 F, according to the catalog notes.
• Cv 0.35 and 0.16 in. orifice for fine regulation.

Technical specification

Specification of NUSS-FNS2-7

Union bonnet or integral bonnet

Choose the union bonnet when stem packing is expected to need renewal during the life of the plant or when the service is severe enough to wear the seat. Choose an integral bonnet where the valve is rarely touched and the smallest height and lowest leak path count matter. The two catalogs use the same orifice and similar Cv at this size.

Higher temperatures need a different packing. The standard packing keeps the valve to 450 F; where steam tracing or hot process fluids exceed this, the catalog lists PEEK and graphite packings, and the order code must be changed accordingly.

Thread size matters: 1/8 in. NPT is common on gauge and transmitter connections. For tube connections, other codes in the same series use FITOK ends in place of FNS2.

Installation notes

Use a clean thread sealant, apply it only to the male thread and keep it out of the valve bore. At 6,000 psig a small amount of debris in the seat can cause a leak that is hard to cure.

Before the first pressurization, open the valve slightly and pressurize slowly to confirm that the bonnet nut and packing are tight. Tighten only with the line depressurized.

Typical GCC use

General engineering note: 6,000 psig needle valves in this size are typically used at wellhead instrument lines, hydraulic test stands, high-pressure gas analyzers and chemical injection skids in oil and gas and petrochemical facilities. Because stainless steel resists chloride attack better than plated carbon steel, it suits coastal and offshore-adjacent sites. Verify the project specification for fluid and certification needs.

Related FITOK catalogs

FITOK lists integral bonnet needle valves, ball valves, check valves and manifolds that fit the same instrument lines. Matching adapters and plugs in 316 stainless steel can be quoted with this valve on request.

Frequently asked questions

What is the pressure rating of NUSS-FNS2-7?

The product page gives 6,000 psig (414 bar) between -65 F and 450 F (-54 C and 232 C).

What does FNS2 mean?

FNS2 is a 1/8 in. female NPT end connection.

Can the stem be serviced in the line?

Yes, the union bonnet nut can be released so that the stem assembly can be removed while the body stays connected.

Which packings extend the temperature range?

The catalog notes PEEK packing to 500 F and graphite packing to 1,200 F; these change the order code.

Is Seven Star LLC a FITOK distributor?

No, we are an independent supplier in Muscat and supply FITOK items on request rather than acting as a FITOK channel partner.

Documents and quotation

For quotation, send your required quantity and destination. The FITOK datasheet and user manual for NUSS-FNS2-7 are provided below the description on this page. Seven Star LLC works as an independent supplier from Muscat. Please compare code, ratings and options with the documents before you place an order; see also the category listing.