Flowline
Union crossovers, bull plugs and lift subs
The small parts that make a flowline fit together: crossovers between figures, sizes and threads, changeovers between genders, and bull plugs, gauge plugs and lift subs for union ends.
A union crossover joins two different connections, for example 3 in FIG 1502 to 2 in FIG 1502, FIG 1002 to FIG 1502, or a union end to a line pipe, tubing or butt weld end, while a changeover joins two union ends of the same gender. Union bull plugs close a union end, gauge plugs add a port for a pressure gauge, and lift subs give union-ended iron a lifting point. We make all of them in AISI 4130 from one piece, rated and marked for the lower of their two ends.
Crossovers and changeovers
| Type | What it joins | Example |
|---|---|---|
| Size crossover | Two sizes of the same figure | 3 in FIG 1502 female by 2 in FIG 1502 male |
| Figure crossover | Two figures, where the lower rating governs | 2 in FIG 1002 female by 2 in FIG 1502 male, rated 10,000 psi |
| Union to thread | A union end and a threaded end | 2 in FIG 1502 female by 2 in line pipe or 2-7/8 in EUE tubing thread |
| Union to weld | A union end and a butt weld end | 3 in FIG 1502 male by 3 in XXS butt weld |
| Changeover | Two union ends of the same gender | 2 in FIG 1502 female by female |
Ends are read in the order they are written. Male ends are supplied with their wing nut.
A crossover is never rated higher than its weaker end. A union-to-thread crossover is limited by the pressure the thread and the pipe behind it can carry, which for line pipe and tubing threads is usually below the 15,000 psi of a FIG 1502 union, and it is marked with that lower rating so it cannot be mistaken for a full-rated part.
Bull plugs, gauge plugs and lift subs
| Part | What it does | Options |
|---|---|---|
| Union bull plug | Closes a male or female union end, for testing or a dead end in a manifold | Male (with wing nut) or female; solid or with a bleed port |
| Gauge plug | Closes a union end and carries a pressure gauge, transducer or needle valve | Usually 1/2 in NPT ports; number and size to order |
| Lift sub | Gives union-ended iron a lifting eye or bail, so it can be handled by crane | Made to the figure and size of the iron it lifts, and to your lifting drawing |
A lift sub is lifting equipment as well as a pressure part. Give us the load, the sling arrangement and any proof test your lifting procedure requires; they are written into the quotation, the drawing and the certificate.
Material, rating and marking
Crossovers and plugs are machined from AISI 4130 forgings or bar, quenched and tempered, with one-piece bodies so there is no weld between the two ends. Each part is stamped with both end descriptions, the cold working pressure of the weaker end and the heat number. For hydrogen sulfide service they are made to NACE MR0175 / ISO 15156-2 hardness limits and marked as sour parts.
We make these parts to the API 6A and API 16C 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
Crossover, 3 in FIG 1502 female by 2 in FIG 1502 male, one piece, AISI 4130 quenched and tempered, 15,000 psi CWP standard service, EN 10204 3.1, 6 pcs
Gauge plug, 2 in FIG 1502 female, two 1/2 in NPT ports, AISI 4130 quenched and tempered, 15,000 psi CWP, EN 10204 3.1, 4 pcs
Frequently asked questions
What pressure is a crossover rated for?
The lower of its two ends. A crossover from 2 in FIG 1502 to 2 in line pipe thread is limited by the thread, not by the union, and it is marked with that lower rating. Check the marking before it goes into a line.
What is the difference between a crossover and a changeover?
A crossover joins two different figures, sizes or connection types. A changeover keeps the figure and size but changes the gender, for example female by female, so two male ends can be joined.
What thread goes in a gauge plug?
Usually a 1/2 in NPT port for a pressure gauge, transducer or needle valve, but the tapping is made to your order. Tell us the port size and how many ports you need.
Can a lift sub be used on any union?
Only on the figure and size it is made for, and only within the load it is rated for. Lifting gear is covered by your own lifting procedure; give us the load and any proof test it requires and both go into the quotation.