TECTULby IMR

Fluid conveyance · Carbon steel gate valves

TECHNICAL DATA SHEET

FT-TC-VAL-COMPUERTA-AC-001

Issue date: August 4, 2026 · Rev. 001

Check the current version

Carbon steel gate valve — cast flanged API 600 class 150 and forged compact API 602 class 800

TECTUL · Dispatch across Colombia · Exports to Central & South America

TECTUL's carbon steel gate valve in two constructions that share material but not product standard: the cast flanged version in A216 WCB per API 600 (solid wedge, bolted bonnet, outside-screw-and-yoke stem, class 150 flanged ends per ASME B16.5), and the forged compact version in A105 per API 602 (threaded NPT or socket-weld ends, 1/2″ to 2″, class 800). Both are read under the same ASME B16.34 pressure-temperature framework, just in different class columns. This sheet corrects a naming error in our own catalog: the forged reference we call "800 psi" does not carry an 800 psi rating — it is API 602/B16.34 Class 800, whose cold pressure ceiling is 1,973 psig (136 bar) at 38 °C, almost seven times its commercial name.

SKU VT-valvula-compuerta-acero-al-carbon-bridada · 2 constructions: cast flanged class 150 (2″–12″) and forged compact class 800 (1/2″–2″, catalog alias)

1. Technical specifications

Two constructions, one material

Pressure-temperature table — class 150 cast (A216 WCB, B16.34 group 1.1)

Pressure-temperature table — class 800 forged (A105, B16.34 group 1.1)

Class 150: values published directly in Table 2-1.1 of ASME B16.34 for material group 1.1. Class 800: not a direct column of the table — obtained by linear interpolation, 1/3 of class 600 + 2/3 of class 900 of the same group 1.1, a method documented in industry practice around the standard and used by API 602 line manufacturers (see section 2 for the calculation detail). The 38 °C anchor value (1,973 psig) is verified against the figure published by API 602 line manufacturers; the higher-temperature points are the same interpolation applied at each temperature step and should be checked against the manufacturer's full table before a critical design.

Face-to-face dimensions — cast flanged, class 150 (ASME B16.10)

Gate valve pattern with raised face (RF), class 150 flanged ends per ASME B16.5 (bolt circle and stud count set by the same nominal size). The forged compact class 800 has no F2F table in B16.10 because no flanged version of that class exists (section 2); its face-to-face dimension is set by API 602 and the manufacturer of the reference — confirmed on quotation.

2. The accuracy correction: "800 psi" is actually Class 800

A commercial name that does not match the engineering

The catalog names the forged reference "Válvula Compuerta Acero Al Carbón 800 Psi". That name suggests an 800 psi WOG/CWP rating, in the style of the 600/1000/2000/3000 WOG threaded ball valve line. That is not correct. The reference follows API 602 and its rating is ASME B16.34 Class 800 — a pressure-temperature class, not a WOG number — whose cold ceiling (−29 to 38 °C) is 1,973 psig (136 bar): almost 2.5 times the number in the commercial name.

This sheet corrects the name in the technical content: where the catalog says "800 psi" it should read "Class 800". The correction is not cosmetic — a buyer designing around 800 psi as the real ceiling is leaving more than 1,100 psi of margin the valve actually has on the table, or worse, comparing it against another reference that really is 800 psi WOG and reaching the wrong capacity conclusion.

Why Class 800 does not appear in the standard B16.34 table

ASME B16.34 publishes columns for class 150, 300, 400, 600, 900, 1500, 2500 and some intermediates, but Class 800 is calculated, not read directly, through linear interpolation between Class 600 and Class 900 of the same material group:

That is the underlying reason why Class 800 has no flanged version: being an interpolated class and not a standard flange class, ASME B16.5 defines no flange pattern for it. That is why Class 800 only exists threaded or socket-weld (API 602), never flanged — and why our cast flanged valve in this same sheet is Class 150, not Class 800: they are two products under different construction standards, not two points on the same pressure ladder.

The steel standards ladder: who governs what

This table is the map that summarizes which standard decides each figure in the sheet: if a valve datum does not fit the correct standard for its construction (for example, looking for F2F in B16.10 for the forged one, or a WOG rating for the flanged one), the error is in the standard consulted, not in the valve.

3. Why API 600 requires an OS&Y stem, trim numbers and graphite packing

Outside-screw-and-yoke stem (OS&Y): mandatory under API 600

API 600 requires the flanged gate valve to have an outside screw and yoke stem: the thread that raises and lowers the wedge stays outside the body, in the yoke visible above the bonnet, instead of being submerged in the process fluid as in an inside-stem design. Two engineering reasons justify it in plant steel valves:

• Visual position indication. The stem protrudes further when the valve is open and retracts when closed: an operator sees the valve's state from a distance, with no extra instrumentation — critical in valve rooms and process lines where confirming "open" or "closed" at a glance prevents wrong maneuvers.
• The thread never touches the fluid. On an inside stem, the actuating thread is exposed to the process fluid — steam, hydrocarbons, chemicals — and it degrades, scales or galls. With OS&Y the thread operates in air, lubricated, protected by the yoke, which extends its life and keeps operating torque stable over the years.

The forged Class 800 compact valve does not always carry OS&Y: in small sizes (1/2″–2″) many manufacturers use a non-rising inside stem to keep the compact design, since API 602 does not mandate OS&Y with the same force as API 600. The stem type of each reference is confirmed on quotation.

API trim numbers: what each one combines

The "trim" is the material combination of the moving wetted parts — seat, wedge/disc and stem — and API 600 identifies them by number, a practice extended to steel valves generally:

The trim number is not a catalog whim: it sets erosion resistance (Stellite trims, 5 and 8, serve in high-velocity steam and fluids with particles), chemical resistance (Monel for seawater and reducing acids, 316 for moderate chlorides) and the relative hardness between seat and wedge (a hardness difference between the two sealing surfaces is required so they do not gall against each other). The exact trim of each catalog reference is confirmed on quotation.

Graphite packing: why not PTFE in this family

The PTFE-sealed threaded ball valve seals with a polymer that tolerates up to ≈180 °C. The carbon steel gate valve, by contrast, usually works in steam and process lines above that limit, where PTFE degrades. That is why the stem seal in this family is flexible graphite packing, compressed in the packing box by the gland: graphite tolerates temperatures far above PTFE, does not burn, and is the industry reference material for steam and high-temperature steel valves. Its trade-off is that it requires periodic gland re-tightening — the graphite settles with use — and a pitting-free stem surface, because a scored surface opens a leak path that no amount of extra tightening closes.

4. Frequently asked questions

Does the "800 psi" carbon steel gate valve really only take 800 psi?

No — it takes far more. The reference is ASME B16.34/API 602 Class 800, whose real cold ceiling (−29 to 38 °C) is 1,973 psig (136 bar). The commercial name "800 psi" is a legacy simplification that confuses the class number with a WOG rating; this sheet uses the verified figure. The value decreases with temperature (section 1).

What is the pressure of the class 150 flanged gate valve?

285 psig (19.6 bar) at 38 °C, per ASME B16.34 material group 1.1 (A216 WCB), decreasing to 125 psig (8.6 bar) at 343 °C. It is this sheet's cast flanged construction, distinct from the forged Class 800 one.

Why does Class 800 not exist flanged?

Because it is an interpolated class (1/3 of Class 600 + 2/3 of Class 900), not one of the standard flange classes of ASME B16.5. With no flange pattern of its own, it is only manufactured threaded or socket-weld under API 602. If the project needs high-pressure flanged service, the answer is moving up to Class 600 or higher of B16.5, not looking for a "flanged Class 800."

What is the difference between this valve and an 800 WOG ball valve?

The rating system is different: 800 WOG is a manufacturer's cold pressure for a threaded ball valve, not an ASME class (ASME class 800 does not appear directly in B16.34: it is interpolated, see section 2). A Class 800 API 602 gate valve and an 800 WOG ball valve may share the number in their name and have completely different pressure capacities; they cannot be compared by the number alone.

Do I always need an OS&Y stem?

On the API 600 flanged valve, yes — the standard requires it and it is this sheet's reference construction. On the forged compact Class 800 valve, many manufacturers use an inside stem in small sizes to keep the compact design; the stem type of each reference is confirmed on quotation.

What trim should I request for high-velocity steam?

A trim with Stellite-hardfaced surfaces (Trim 5 or 8 from the section 3 table), which resists high-velocity steam erosion better than a plain 410 trim (Trim 1). The exact trim per reference is confirmed on quotation.

5. Application notes

6. Technical notice and limitation of liability