Flowline
Check valves for flowline iron
Check valves keep flow moving one way: from the pumps to the well, never back. Flapper checks for liquids and slurries, top entry checks that service in line, and dart checks for gas.
A flowline check valve lets fluid pass from the pump towards the well and closes against flow in the other direction, protecting pumps and lines if pressure reverses. We supply three types with hammer union ends: inline flapper checks for liquids and slurries, top entry flapper checks that can be serviced without leaving the line, and dart checks for nitrogen, CO2 and other gas at high velocity, in sizes from 1 to 4 in and ratings up to 15,000 psi.
Three types
| Type | How it closes | Best for |
|---|---|---|
| Inline flapper | A hinged flapper swings shut onto its seat when flow reverses | Liquids and slurries, including frac fluid and cement |
| Top entry flapper | As the inline flapper, with a removable top cap for access | Lines where valves are inspected or repaired in place |
| Dart | A spring-loaded dart closes on its seat, opened by forward flow | Nitrogen, CO2 and other gas at high velocity |
Union makers publish ranges such as inline flapper checks in 1 to 3 in at 15,000 psi and top entry checks in 2 to 4 in from 6,000 to 15,000 psi, with sour versions at lower ratings. We quote each valve at the size, figure, rating and service on your order.
Flapper or dart
A flapper gives a nearly full bore when open, so it passes slurries and solids with little pressure loss. In high-velocity gas the flapper can flutter and wear the hinge and seat. A dart check closes positively under spring force and suits gas service, at the cost of a more restricted flow path. Pumping nitrogen or CO2 is the usual reason to choose a dart.
A check valve installed against the flow direction blocks the line. The flow arrow is stamped on every body; confirm it at each rig-up.
Sour service, testing and marking
For hydrogen sulfide service, bodies and internals are made within the hardness limits of NACE MR0175 / ISO 15156, seals are chosen for sour gas and the valve carries the sour rating. Each valve is shell tested to the pressure on your order and stamped with type, size, figure, rating, flow direction and heat number. EN 10204 3.1 certificates cover the pressure-containing parts.
We make these parts to the API 6A requirements your order calls up: material, dimensions, tests and marking as specified. We do not hold an API license, so the parts do not carry the API Monogram. If your specification requires monogrammed equipment, the quotation says so plainly.
Ordering
Check valve, top entry flapper type, 3 in FIG 1502 male by female, 15,000 psi CWP standard service, shell tested at 22,500 psi, EN 10204 3.1, 4 pcs
Check valve, dart type, 2 in FIG 1502 male by female, 15,000 psi CWP, for nitrogen service, EN 10204 3.1, 2 pcs
Frequently asked questions
Which check valve for nitrogen or CO2?
A dart check. Its spring-loaded dart closes positively against gas flowing at high velocity, where a flapper can chatter and wear. Flapper checks suit liquids and slurries.
Can a check valve be installed either way round?
No. Every check valve has a flow direction, cast or stamped as an arrow on the body. Installed backwards it blocks the line. Check the arrow against the pump direction at every rig-up.
What is a top entry check valve?
A flapper check whose cap unscrews from the top of the body, so the flapper and seal can be inspected or replaced without taking the valve out of the line.
Do you supply spare flappers, darts and seals?
Yes. Repair parts for each valve type, size and rating can go on the same order as the valves.