Wafer Butterfly Valves · Purchase-decision comparison
Wafer vs lug butterfly valves (SS316L)
Both executions are API 609 SS316L-body butterfly valves for isolation and throttling — the decision is what the pipe around the valve needs to keep doing. This table compares the two executions we publish specification pages for, using only fields that mean the same thing and are collected on the same basis for both. Where a figure is not established by the collected evidence, the cell says so and asks you to confirm it at RFQ.
Last updated: 2026-10
Comparison table
A row appears only where the field means the same thing and is collected on the same basis for both columns. A cell without collected evidence says "confirm at RFQ" — it is never filled with an assumption, and it never implies either execution cannot be supplied.
Quick decision
These conclusions apply to the two executions compared on this page — not to the wafer butterfly valves family as a whole. Other executions of the same family differ, and any value marked "confirm at RFQ" is settled by the quotation, not by this table.
- Line can be drained on both sides for valve work, especially large bores → wafer (DN50–DN2000).
- Piping must stay serviceable under isolation, or dead-end duty is in the design → lug (DN40–DN300).
- Everything else is shared in the collected evidence — seat compound, size and pressure class are confirmed against your medium on the RFQ.
| Field | SS316L Wafer Butterfly Valve | SS316L Lug Butterfly Valve |
|---|---|---|
| Working principle | ||
| Body pattern The defining difference of the comparison: how the body attaches to the line. | Wafer — the valve clamps between the line flanges (sandwich installation) | Lug — threaded lugs; each side of the body bolts to its flange independently |
| Isolation & dead-end capability Same meaning: what stays serviceable when the valve isolates. Stated explicitly on both pages. | No dead-end service; no downstream piping disassembly under load — both line sides are clamped in the valve | Isolates for maintenance or dead-end service — piping on one side stays serviceable while the other is removed |
| Ratings & size | ||
| Size range The ranges do not overlap in scale: the lug page covers the DN40–DN300 utility band, the wafer page extends to DN2000 — larger bores move to wafer on weight and cost. | DN50 to DN2000 | DN40 to DN300 |
| Pressure class | PN10 to PN40, Class 150 | PN10 to PN40, Class 150 |
| Materials | ||
| Seat materials Collected lists differ by one compound: the wafer page additionally lists Viton. Confirm the seat compound against the medium at RFQ. | EPDM, NBR, Viton, PTFE | EPDM, NBR, PTFE (Viton not listed for this execution) |
| Body materials Same meaning (available body constructions); both pages list SS316L among broader material options. | SS316L, Carbon Steel, Cast Iron, Ductile Iron | SS316L, Carbon Steel, Cast Iron, Ductile Iron |
| Disc materials | Aluminium Bronze, Carbon Steel, Cast Iron, Ductile Iron, SS304, SS316 | Aluminium Bronze, Carbon Steel, Cast Iron, Ductile Iron, SS304, SS316 |
| Stem materials | SS410, SS420, SS416, SS304, SS316, Monel | SS410, SS420, SS416, SS304, SS316, Monel |
| Packing | Graphite, PTFE | Graphite, PTFE |
| Connections & operation | ||
| Operation | Lever Operated, Gear Operated, Electric Actuated, Pneumatic Actuated | Lever Operated, Gear Operated, Electric Actuated, Pneumatic Actuated |
| Standards & duty | ||
| Standards Identical basis for both executions: API 609 design, API 609 / MSS SP-67 / MSS SP-68 face-to-face, ASME B16.5 / DIN 2501 flanges, API 598 testing. | Design: API 609; face-to-face: API 609, MSS SP-67/68; flanges: ASME B16.5, DIN 2501; testing: API 598 | Design: API 609; face-to-face: API 609, MSS SP-67/68; flanges: ASME B16.5, DIN 2501; testing: API 598 |
- Specified
- Differs — read the note
- Unverified — confirm at RFQ
- Conditional — confirm at RFQ
How to choose
Choose wafer for sandwich installation and large diameters
The wafer execution is the compact, light isolating and throttling valve for large bores — its collected page runs DN50 to DN2000 at PN10–PN40 / Class 150. It fits wherever the line can be drained on both sides for valve work and dead-end duty is not part of the design. The low-carbon SS316L body option is for welded installation where sensitization matters, and disc material is matched to the medium against the body — the collected page lists six disc grades for exactly this reason.
Choose lug where piping must stay serviceable under isolation
Upstream or downstream piping that must be maintained without draining the whole line, or dead-end duty, is the stated case for the lug execution. The trade is the size band: DN40 to DN300, the common utility range. Its seat list on the collected page is EPDM, NBR and PTFE; if your medium calls for a Viton compound, confirm availability at RFQ.
Everything else is shared — decide on the body pattern
Pressure class, disc and stem materials, packing, operation options and the full standards basis (API 609, MSS SP-67/68, ASME B16.5 / DIN 2501, API 598 testing) are identical in the collected evidence. The body pattern — and the isolation behaviour that follows from it — is the decision.
Frequently asked questions
When is the lug pattern required instead of wafer?
When the pipe must keep working around an isolated valve. A wafer body is clamped between both flanges, so taking it out — or removing the downstream spool — means draining and opening the line on both sides, and the pattern is not rated for dead-end duty. The lug body bolts to each flange independently, so one side stays pressurised while the other is dismantled, and dead-end service is within the design. If neither case applies, wafer is the lighter and — in the large diameters only execution covering it — the cheaper route.
Why is the lug size range so much smaller (DN40–DN300 vs DN50–DN2000)?
That is what the two collected pages cover, and it matches normal practice: threaded-lug bodies carry the flange load in the body itself, which stops scaling economically — larger bores move to wafer or double-flanged executions on weight and cost. If you need lug-pattern behaviour above DN300, raise it in the RFQ rather than assuming; the substitution to a double-flanged execution is a piping decision.
Why do some cells say "Unverified — confirm at RFQ" or mark a difference?
This page only states figures the collected evidence supports. Where the two source pages differ — the wafer page lists a Viton seat compound the lug page does not — the cell is marked rather than silently mixed. Attach your medium, temperature and size to the RFQ; the seat compound and current ranges are confirmed in the quotation.
Individual execution specification pages
Each execution compared above has its own page — full specification table, selection guidance and RFQ details.
Ordering & documentation
Documents
Ask for the documentation set with the inquiry — typical items (material certificates, test reports to the listed inspection standard, dimensional drawings) are confirmed and supplied with the quotation.
Quotation
Send the medium, temperature, pressure, size and connection for a quotation-ready inquiry. Lead time, MOQ and price are confirmed at quotation, together with the documents to be supplied with the order.
Sample & supply
Supply terms, order quantities and lead time are agreed per order — state the destination country and required schedule with the inquiry.
Storage & shipping
Store valves with seats and seals protected from UV, ozone and deformation, and keep end-face protectors on until installation; storage limits and shipping arrangements for the selected materials are confirmed at quotation.
Knowledge: selection guides
Request a quote
Send size, pressure class, set pressure and service conditions for a quotation-ready inquiry — the execution is confirmed against figures, with documents and terms.
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