On a corrosive service RFQ, a separator is not a commodity line item — it is a wetted-alloys decision that must be made before the steam trap, strainer, and insulation jacket are quoted. Skipping the body-material call-out or the ΔP envelope forces a 3–7 day requote cycle and, worse, ships a carbon-steel baffle separator (ASTM A106-B body, ASTM A-234 WPB end caps) into a chloride or sour-condensate duty where pitting shows up inside two quarters.
This article walks the RFQ line by line: what separator datasheets typically specify (including maximum operating pressure, maximum operating temperature, body material, connection type, and discharge capacity), what corrosive service requires in terms of material upgrades, and common omissions in separator quotations.
Separator Type vs Service Severity: Baffle vs Cyclonic vs Vortex
Baffle-type (multi-change-of-direction) separators such as the Eliminator Series (Leslie Controls) operate up to 600 psig (41.4 barg) and 650 °F (344 °C), with removal of nearly all moisture and solids above 10 microns and capacities to 35,000 lb/hr — but are sold standard with carbon steel bodies, baffles, and end caps, which is a non-starter for chloride, sour, or acidic condensate [S2]. Cyclonic / vortex units, including the DC3S cast-iron / DC5S bronze range from TLV, are typically PMO 230–300 psig and TMA 428 °F (220 °C), with separation efficiency up to 98% through combined centrifugal, impingement, and gravity stages [S6][S9]. For critical or corrosive service, vertical vortex geometry is recommended in vendor literature specifically because it keeps condensate on the wall film and off the baffle crevices that trap chloride pitting [S3].
The 2026 short-list for a corrosive RFQ therefore almost always reduces to a vertical vortex separator in 316/316L stainless, with a separate mechanical orthermodynamic steam trap mounted on the bottom drain — never an integrated trap-station unit in cast iron or bronze.
The 8 Mandatory RFQ Fields (and the 4 That Force Requote)
Every separator vendor in the research material asks the same four sizing inputs, and every quote desk adds four more fields once corrosion is on the datasheet [S2][S3]: (1) Fluid — saturated steam, superheated steam, or compressed air/gas; (2) Maximum flow rate in lb/hr or kg/hr; (3) Connection size in inches or DN; (4) System pressure (psig or barg). For corrosive service you must also state (5) Max operating temperature TMA in °F or °C; (6) Allowable pressure drop ΔP across the separator (typically ≤0.5 psi on a clean design); (7) Inlet steam quality and target outlet dryness (industry default is 2–3% moisture, i.e. 97–98% dryness) [S3]; and (8) Wetted-parts material call-out — 316/316L stainless as default, with optional upgrade to duplex, Alloy 20, or titanium if chloride or H₂S partial pressure warrants it.
The four RFQ fields that drive requote cycles are: omitting TMA (vendors default to 300 °C / 572 °F and may not match your flange class), omitting ΔP (forces the vendor to assume 1.0–2.0 psi and oversize the body), stating only a connection size without confirming whether it must equal the line size (line-size rule applies to non-critical drainage only) [S3], and failing to call out the trap station. The Eliminator Series spec sheet explicitly states "Always install a Steam Trap after the Steam Separator" and "Always install a Y Strainer between the Steam Separator and Trap" — those two auxiliaries are not optional accessories, they are part of the working assembly [S2].
Materials of Construction for Corrosive Wetted Parts
Standard carbon-steel separator builds use ASTM A106-B body, ASTM A-234 WPB end caps, ASTM A-105 couplings/plugs/end connections, and ASTM A 569 baffles — the Eliminator Series baseline [S2]. Vira's datasheet offers Carbon Steel as standard with Stainless Steel as optional for both body and interior, and that optional upgrade is the actual decision on a corrosive RFQ [S3]. TLV's DC3S ships in cast iron (FC250) at 300 psig PMO, and the DC5S in bronze (CAC407) at 230 psig PMO — neither belongs in a chloride-bearing or sour condensate service [S6].
For most chemical-plant steam headers carrying trace chlorides, the practical minimum is 316L stainless body and internals (low-carbon grade to avoid sensitisation at the baffle weld HAZ), with ASME B16.5 flanges in the same class as the line flange (typically 150# for headers ≤150 psig saturated, 300# above). If the condensate pH is below 4 or the chloride concentration exceeds ~200 ppm, escalate to duplex 2205 or, in the worst wet sour cases, Alloy 825/20 — but note the cost jump is typically 3–5× the 316L price and lead time stretches from 6–8 weeks to 16–24 weeks for non-standard alloys. Field practice from the geothermal separator literature confirms the geometry that drives this: 30-inch-diameter vessels with optimal inlet velocity 220 ft/s yielded outlet quality of 99.5%, with separator diameter 3× the inlet pipe diameter as a sizing rule of thumb [S5].
Selection Criteria: Baffle vs Cyclonic on a Corrosive Line
Three decision criteria line the two geometries up cleanly for an RFQ reviewer. Pressure drop: baffle types run relatively low ΔP, while cyclonic units run relatively high ΔP because they trade pressure for separation efficiency [S7]. Efficiency bandwidth: baffles hold high efficiency over a wide velocity range; cyclonic units are high-efficiency but only across a narrower velocity band, and above a critical velocity they re-entrain water back into the steam — a real corrosion-acceleration mechanism because wet steam carries chloride directly onto downstream valve seats [S7]. Sizing philosophy: baffles are sized to the pipeline (line-size rule, recommended steam velocity 30 m/s for non-critical drainage), while cyclonic units are sized for maximum efficiency at the design point, not the line size [S3][S7].
For corrosive service the practical reading is: choose a cyclonic / vortex separator sized to the design mass flow with explicit ΔP allocation, not to the line size, and never operate above the critical velocity — or you have re-entrainment plus chloride pitting in one package. A baffle-type unit is acceptable when the line is non-critical (general drainage, heat transfer headers) and the condensate chemistry is proven benign, which is rarely the case on a true corrosive RFQ.
Operating Envelope, Codes, and Trap Integration
The Eliminator Series maximum operating envelope is split by body size: 1/2"–2" units are rated PMO 600 psig (41.4 barg) and TMO 650 °F (344 °C), while 2-1/2"–6" units drop to 150 psig (10.4 barg) / 565 °F (296 °C) on ANSI 150 flanges, 300 psig (20.7 barg) / 650 °F on ANSI 300, and 600 psig (41.1 barg) / 650 °F on ANSI 600 [S2]. Welders are certified to ASME Section 9 and vessels built to ASME Section VIII Division 1 — those are the two pressure-boundary code references you should see on any separator data sheet for a U.S. plant [S2]. For European builds, the equivalent is the Pressure Equipment Directive (PED 2014/68/EU) with CE marking, and for explosive atmospheres the ATEX 2014/34/EU equipment category must be on the RFQ if the separator sits inside a classified zone.
Trap station integration is not an accessory line — it is a process requirement. The Spirax Sarco separator guidance states that "a suitable steam trap should be fitted to the condensate outlet of the separator to ensure the efficient removal of condensate" [S7]. For corrosive service the trap must be in the same alloy family as the separator (316L minimum), sized for the separator discharge capacity (TLV's DC3S discharges up to 2,070 lb/h at 300 psig; DC5S up to 185 lb/h at 230 psig) [S6], and preceded by a Y-strainer to protect the trap seat — exactly the Eliminator installation tip [S2]. A related RFQ pattern for the wetted-auxiliaries chain on the same line is documented in our bellows seal valve spec guide, where trap-station completeness has the same requote impact.
Common RFQ Mistakes and Failure Modes
The five failure modes that show up in field-rejected separator quotes are: (1) Carbon-steel body specified for chloride condensate — visible pitting at baffle welds inside 6–12 months. (2) Connection size used as the only sizing input — undersized separator re-entrains water above 30 m/s line velocity, downstream control valves water-cut. (3) No ΔP allocation — vendor assumes a conservative (high) ΔP and prices a larger alloy body, inflating the quote 20–40%. (4) Trap and Y-strainer omitted from the RFQ line — the separator ships but the assembly is not functional until those two line items are added, doubling the freight and extending the schedule. (5) Saturated pressure quoted without TMA — for superheated steam or steam with a process-side temperature limit above 344 °C (650 °F), ANSI 600 class is mandatory, not optional [S2].
A 30-inch geothermal test unit producing 99.5% dryness at 220 ft/s inlet velocity, with separator diameter 3× inlet diameter and outlet pipe diameter equal to inlet, is the kind of geometry benchmark that lets a reviewer accept or reject a vendor's sizing calculation in one pass [S5]. When that geometry is not visible in the vendor's proposal, it is reasonable to ask for the underlying sizing method before PO release.
Sourcing Channels and 2026 Vendor Landscape
The public 2026 vendor short-list for industrial steam separators splits into three tiers. Tier 1 — global catalogue with published datasheets and ASME/PED code trace: Spirax Sarco, TLV (DC3S/DC5S cyclone line), and Valmet for the pulp-and-paper Steam Separator PF mechanical refiner stage [S1][S6][S7]. Tier 2 — regional packagers with configurable alloy options: Leslie Controls' Eliminator Series (ES-150 / ES-300 / ES-600) with the carbon-steel standard build and the stainless upgrade path [S2]; Vira Industrial with vertical vortex bodies in 1/2"–4" threaded and DN15–DN300 flanged, 16/25/40 bar pressure classes, 300 °C TMA [S3]. Tier 3 — engineering custom shops for geothermal and high-pressure steam: vendors building to the 30-inch, 220 ft/s-inlet benchmark published by the geothermal separator literature [S5].
Specifying a steam separator on a corrosive-fluid RFQ is therefore not a single-line "1 each, 2", 300#" entry — it is a wetted-alloys document that names type (vertical vortex preferred), material (316L minimum, duplex/alloy on escalation), full operating envelope (flow, psig, TMA, ΔP), and the trap-plus-strainer assembly as a single functional line. RFQs that arrive in that shape get priced in 24–48 hours; RFQs that arrive in the line-size-only shape take a week of clarification and routinely come back 30–60% over the engineering estimate. For engineers cross-specifying a steam trap on the same drain line, the same trap-station discipline applies. Vendors that publish a sizing graph keyed off design PSIg and lb/hr — as FD Separators does — give the reviewer a verifiable sizing artefact on the quote, which is the single strongest acceptance signal on a corrosive-service RFQ [S8].
For the relevant spec sheets and selection criteria, see fluid coupling.