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Fluid conveyance · Bronze check valves

TECHNICAL DATA SHEET

FT-TC-VAL-CHEQUE-BRONCE-001

Issue date: August 4, 2026 · Rev. 001

Check the current version

Threaded bronze check valves, ASTM B62 C83600 — the 6 catalog designs under MSS SP-80

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The six threaded NPT check valve designs in ASTM B62 C83600 bronze from the TECTUL catalog, from 1/2″ to 4″ (DN 15 to DN 100): Cheque Universal Napoli with metal-to-metal seat, gate check, Helbert Y-pattern swing check, lift check, Helbert hydro check and air-tank check. They all share the MSS SP-80 dual SWP/WOG class framework, but they do not share a closing mechanism: some close by gravity and others by spring, and that is where the admissible mounting position matrix at the core of this sheet comes from. The selection criterion is not the size but the closing mechanism against the orientation of the line and the water hammer risk.

SKU VT-59231 (Cheque Universal Napoli, metal-to-metal seat) · family of 6 threaded NPT check valve designs in ASTM B62 C83600 bronze

1. Technical specifications

Materials by component

C83600 alloy composition per ASTM B62. The exact spring grade, the pin material and the seat type per figure are manufacturer data for each reference: confirmed on quotation or in the PDF sheet attached to the product.

Regulatory framework and supply conditions

Bronze check valve references in the TECTUL catalog

The air-tank reference is offered in inlet × outlet combinations because it connects the compressor discharge to the tank neck. Face-to-face dimensions, height and weight are not standardized by MSS SP-80 for threaded bronze valves — each manufacturer sets its own pattern — and are confirmed on quotation or in the PDF sheet attached to each reference.

2. MSS SP-80 dual classes (SWP/WOG) applied to bronze

A threaded bronze valve is not rated with a single pressure number. MSS SP-80 defines dual classes: each class carries two ratings, SWP (Saturated Working Pressure, the real thermal limit) and WOG (Water-Oil-Gas, cold non-shock pressure). This is the complete system, and it applies equally to the six check references in this sheet.

¹ Steam saturation temperature at the stated SWP: a thermodynamic property of water, not of the valve. It is the same reference value used by ASME B16.3-2021 (Table 3-1, note 1) for the 186 °C limit of Class 150 threaded fittings. WOG is not an ASME B16.34 class: it is a number declared by the manufacturer in accordance with MSS SP-80.

The two reading rules

Rule 1 — the WOG number only applies cold. The 200, 300 or 400 psi cast on the body apply up to 38 °C (100 °F). Above that temperature the allowable pressure drops, and the absolute steam service limit is set by the SWP of the same class: a "300 WOG" check valve is also a "150 SWP" check valve — at 186 °C it takes 150 psig of steam, not 300 psi.

Rule 2 — SWP and WOG rise together, class by class. The SWP of one class cannot be combined with the WOG of another. When ordering, the class (125, 150, 200 or 300) fixes both numbers at once.

A check valve also has a condition that gate or globe valves do not: it is the only valve on the line that, when closed, always works with a pressure differential in one direction only. The seal is produced by the return flow itself pushing the closure member against the seat; that is why a metal-to-metal seat such as the one on the Cheque Universal does not give bubble-tight shut-off, but retention with the leakage rate inherent to metal contact. When the application requires full tightness in the reverse direction (isolation for maintenance), the check valve does not replace an isolation valve: a ball or gate valve is installed upstream.

3. Mounting position matrix by closing mechanism

A check valve is not interchangeable in position. The mechanism that closes the port —gravity, spring or axial guiding— defines the orientation in which it works reliably, and mounting it against its design principle leaves it permanently open or only partly closed: it loses its function. This is the matrix of the six bronze check designs in the TECTUL catalog, classified by closing mechanism.

Classification by mechanism family (gate and swing by gravity versus spring-loaded piston and ball), applying general check valve installation practice. The admissible position of each reference and the flow direction marked on the body are confirmed in the product PDF sheet or on quotation: the arrow cast on the body always overrides this table.

Why a gravity check valve installed with downward flow loses its function

In gate and swing disc designs, the force that returns the closure member to the seat when flow stops is its own weight. That weight only does its job if it acts opposite to the flow: hence the admissible mounting is horizontal —the disc falls onto the seat— or vertical with upward flow —the disc falls against the stream—.

With downward flow the opposite happens: gravity and the fluid push in the same direction, the opening one. The closure member rests against the open stop and, when flow stops, no force brings it back to the seat. The valve stays permanently open and return flow passes freely. This is the most common field error with this family and it is not detected by the network pressure test: it only shows up when the pump stops and the column comes back, when the tank drains through the filling line, or when the system loses its prime.

The same reasoning explains a second, quieter error: rotating the body about its axis in a horizontal installation. If the cap ends up sideways or facing down, the swing disc no longer falls onto the seat but to one side, and closing then depends only on the push of the return flow. The valve "looks" installed and seals at high differential pressure, but lets return flow through at low velocity.

Field rules

• The arrow cast on the body indicates the flow direction, not the mounting position: complying with the arrow does not guarantee the orientation is correct.
• On a gravity check valve mounted horizontally, the cap always faces up.
• Spring designs (hydro, air tank) close by the spring and not by weight, and therefore tolerate more orientations; even so, confirm with the manufacturer's sheet before installing with downward flow.
• Leave a straight run upstream, free of elbows, pumps and immediate reducers, so that the closure member works with steady flow and does not chatter against the seat.
• Size by the service flow rate, not by the pipe diameter: an oversized check valve works with the closure member partly open, vibrates and wears the seat. This is the minimum full-lift velocity principle covered by Crane TP-410; the specific coefficient depends on the check type and is taken from the manufacturer's sheet.
• A check valve is not an isolation valve: to work on the line, an isolation valve is installed upstream.

4. Closing water hammer: gravity versus spring

When a pump stops, the moving liquid column decelerates, stops and reverses back toward the pump. The check valve must close before that reversal gains speed. If it closes late, the closure member seats against a mass of water already travelling backwards and abruptly cancels that velocity: this sudden stop is what generates the overpressure (closing water hammer, or slam). The magnitude of the surge does not depend on the working pressure of the network, but on the reverse velocity present at the instant the closure member touched the seat.

Hence the practical difference between the two groups in this family:

What this sheet does not solve. The magnitude of the transient overpressure depends on the velocity being cancelled, on the fluid density and on the pressure wave celerity in the pipe (Joukowsky relation), and that celerity is set by the pipe material, diameter and wall thickness, not by the valve. Line length, pumping set inertia and the actual valve closing time also come into play. None of these is a property of the check valve, and therefore no overpressure figure is given here: the transient calculation and the decision to install control devices belong to the project engineer under the applicable code (ASME B31.1 or B31.3 for process piping, or whichever governs the network).

When the transient analysis shows that a threaded check valve is not enough, the TECTUL catalog offers the specific lines for the case: a ductile iron non-slam check valve and a surge anticipating relief valve, each with its own data sheet.

5. Frequently asked questions

In what position is a bronze check valve installed?

It depends on the closing mechanism, not on the size or the brand. Gravity designs —Cheque Universal, gate check and Y-pattern swing check— are installed horizontally with the cap facing up, or vertically with upward flow; never with downward flow. Spring designs —hydro check and air-tank check— tolerate more positions because closing does not depend on the weight of the closure member, but this is confirmed with the manufacturer's sheet. The complete matrix is in section 3.

Can I fit a check valve on a vertical pipe with the water flowing down?

Not with gravity designs. With downward flow the weight of the closure member pushes in the same direction as the fluid, that is, toward opening: the valve stays permanently open and the return flow passes freely. If the line runs downward and the layout cannot be changed, the answer is a spring design, confirming with the manufacturer that the figure accepts that position.

Which bronze check valve goes on a pump discharge and which on a compressor?

The catalog directs the Check Hidro Helbert (spring-loaded piston, 1″ to 4″) to hydraulic networks and pump discharge, and the Check Tanque Aire Bronce (spring-loaded disc or ball, with inlet × outlet combinations) to compressor discharge into the air tank. In both cases the spring is what allows fast closing that is less dependent on position.

How much pressure does a bronze check valve take, and is it suitable for steam?

Under MSS SP-80 the answer is two numbers, not one: the cold WOG and the saturated steam SWP of the same class. A Class 125 check valve takes 200 psi cold and 125 psig of steam at ≈178 °C. None of the six references in this sheet publishes its class, so the exact value is confirmed on quotation with the PDF sheet or the factory certificate.

Why is the Cheque Universal the cheapest of the group?

Because it is the simplest design: a swing disc with a metal-to-metal seat, no spring, no elastomer and fewer machined parts. That same simplicity marks its limit: metal-to-metal closing gives retention, not bubble-tight shut-off, and closing depends entirely on gravity, which makes the mounting position more restrictive.

Should I order the check valve in the same size as the pipe?

Not always. A check valve is sized by the service flow rate, so that the closure member is fully open: if oversized, it works partly open, chatters and wears the seat. In sizes where the actual flow is low relative to the pipe, review the operating point before ordering by nominal diameter.

6. Application notes

7. Technical notice and limitation of liability