When servicing a Flowserve Durco Mark III ANSI process pump, knowing the correct POS (Part Ordering System) code is essential for accurate parts identification and ordering. Every component on the Mark III — from the casing to the smallest O-ring — is assigned a unique POS number. This comprehensive breakdown covers all standard POS codes for the Durco Mark III pump family across Group I (1K), Group II (2K), and Group III (3K) frame sizes.
As an independent aftermarket manufacturer with 15+ years of experience producing ANSI B73.1 pump parts, we supply 100% dimensionally interchangeable replacements for every POS code listed below. All parts are manufactured with full EN 10204 3.1 material traceability and undergo PMI (Positive Material Identification) verification before shipment.
Durco Mark III Pump Anatomy — Parts by Location
The Durco Mark III pump can be divided into three major assemblies. Understanding where each POS code sits within the pump helps with maintenance planning and troubleshooting.
- Wet End (Fluid End): Parts that contact the pumped fluid — casing (100), impeller (104), rear cover plate (108), gaskets and O-rings.
- Power End (Bearing Frame): Parts that transmit and support the rotating assembly — shaft (107), bearings (130/131), bearing housing (129), oil seals (125/136).
- Seal Chamber: The interface between wet end and power end — mechanical seal (201A), gland (201C), hook sleeve (201B), packing (119).
Complete Durco Mark III POS Code Reference Table
All standard POS codes for the Flowserve Durco Mark III process pump, with available material options and our aftermarket equivalent availability:
| POS Code | Part Name | Assembly | OEM Material Options | Our Aftermarket Availability | Typical Lead Time |
|---|---|---|---|---|---|
| 100 | Casing (Volute) | Wet End | WCB, 316SS (CF8M), CD4MCu, Alloy 20 (CN7M), Monel, Nickel, Hastelloy B/C, Titanium | ✅ All materials | 8-10 weeks |
| 104 | Impeller (Reverse Vane) | Wet End | 316SS (CF8M), CD4MCu, Alloy 20 (CN7M), Monel, Nickel, Hastelloy B/C, Titanium | ✅ All materials | 8-10 weeks |
| 105 | Impeller Gasket | Wet End | Aramid Fiber with EPDM, PTFE, Graphite | ✅ All materials | 24-48h (stock) |
| 107 | Shaft | Power End | SAE 4140, 316SS, Alloy 20, Monel, Nickel, Hastelloy | ✅ All materials | 6-8 weeks |
| 108 | Rear Cover Plate | Wet End | WCB, 316SS (CF8M), CD4MCu, Alloy 20 (CN7M), Monel, Nickel, Hastelloy B/C, Titanium | ✅ All materials | 8-10 weeks |
| 109 | Rear Cover Gasket | Wet End | Aramid Fiber with EPDM, PTFE | ✅ All materials | 24-48h (stock) |
| 109A | Bearing Housing Adapter | Power End | Ductile Iron, Cast Steel | ✅ All materials | 4-6 weeks |
| 110 | Bearing Housing Foot | Power End | Cast Iron / Ductile Iron | ✅ Standard | 3-4 weeks |
| 111A | Shim (Adapter-to-Casing) | — | 304SS | ✅ Standard | 24-48h (stock) |
| 112 | Gland — Packing Option | Seal Chamber | Cast Iron (Ductile Iron for STX Group) | ✅ Standard | 3-4 weeks |
| 114 | Stud — Gland | Seal Chamber | Steel, 304SS | ✅ All materials | 24-48h (stock) |
| 115 | Hex Nut — Gland | Seal Chamber | Steel, 304SS | ✅ Standard | 24-48h (stock) |
| 115A | Packing Seal Cage Halves (Optional) | Seal Chamber | Glass-Filled Teflon® | ✅ Standard | 1-2 weeks |
| 119 | Packing (Optional) | Seal Chamber | Teflon® Impregnated Fibers, Graphite | ✅ All materials | 24-48h (stock) |
| 120 | Deflector — Inboard (Optional) | Power End | — | ✅ On request | 1-2 weeks |
| 122 | Stud — Casing | Wet End | Steel, 304SS | ✅ All materials | 24-48h (stock) |
| 124 | Hex Nut — Casing | Wet End | Steel, 304SS | ✅ Standard | 24-48h (stock) |
| 125 | Oil Seal — Inboard | Power End | Carbon-Filled Teflon® with Viton O-ring (Labyrinth type) | ✅ INPRO VBXX compatible | 24-48h (common sizes) |
| 129 | Bearing Housing | Power End | Cast Iron / Ductile Iron | ✅ Standard | 4-6 weeks |
| 130 | Bearing — Inboard | Power End | Double Row Angular Contact (SKF or equal) | ✅ SKF/equivalent | 24-48h (stock) |
| 131 | Bearing — Outboard | Power End | Single Row Deep Groove (SKF or equal) | ✅ SKF/equivalent | 24-48h (stock) |
| 133 | Oil Slinger (Optional) | Power End | — | ✅ On request | 1-2 weeks |
| 134 | Locknut — Bearing | Power End | Steel | ✅ Standard | 24-48h (stock) |
| 135 | Lockwasher — Bearing | Power End | Steel | ✅ Standard | 24-48h (stock) |
| 136 | Oil Seal — Outboard | Power End | Carbon-Filled Teflon® with Viton O-ring (Labyrinth type) | ✅ INPRO VBXX compatible | 24-48h (common sizes) |
| 139 | Key — Shaft/Coupling | Power End | Steel, 316SS | ✅ All materials | 24-48h (stock) |
| 140 | O-Ring — Adapter | Power End | Buna Rubber, FKM, FFKM, PTFE | ✅ All materials | 24-48h (stock) |
| 153 | Trico Oiler (Constant Level) | Power End | — | ✅ Standard accessory | 24-48h (stock) |
| 177 | Bearing Housing Drain Plug | Power End | Steel, 316SS | ✅ Standard | 24-48h (stock) |
| 190 | Bearing Housing Vent Plug | Power End | Steel, 316SS | ✅ Standard | 24-48h (stock) |
| 190G | Cap Screw — Foot | Power End | Steel, 304SS | ✅ Standard | 24-48h (stock) |
| 200 | Cap Screw — Bearing Housing | Power End | Steel, 304SS | ✅ Standard | 24-48h (stock) |
| 201 | Cap Screw — Cover/Adapter | Seal Chamber | Steel, 304SS | ✅ Standard | 24-48h (stock) |
| 201A | Mechanical Seal | Seal Chamber | Various (application-specific) | ✅ All types available | 2-4 weeks |
| 201B | Hook Sleeve (Optional) | Seal Chamber | 316SS, Alloy 20, Monel, Nickel, Hastelloy | ✅ All materials | 4-6 weeks |
| 201C | Gland — Mechanical Seal | Seal Chamber | 316SS, CD4MCu, Alloy 20, Monel, Nickel, Hastelloy | ✅ All materials | 3-4 weeks |
| 201E | Gland Gasket | Seal Chamber | Aramid, PTFE, Graphite | ✅ All materials | 24-48h (stock) |
| 245 | Sight Gauge — Bearing Housing | Power End | Glass/Steel | ✅ Standard | 24-48h (stock) |
Additional POS codes available upon request. If your required part number is not listed above, contact our engineering team with your specific requirements.
Durco Mark III Frame Groups & Pump Sizes
The Durco Mark III pump family is organized into three frame groups. Parts are designed to be interchangeable within each group. When ordering, always specify your pump’s ANSI designation (e.g., A60, A70, A80) to ensure correct parts selection.
| Group | Frame | ANSI Designation | Pump Sizes (Suction × Discharge – Max Impeller) | Approx. Weight |
|---|---|---|---|---|
| Group I | 1K | AA | 1K 1.5×1LF-4, 1K 1.5×1-6, 1K 3×1.5-6, 1K 3×2-6 | 97–116 lbs (44–53 kg) |
| AB | 1K 3×2-6 | 103 lbs (47 kg) | ||
| A10 | 1K 1.5×1LF-8, 1K 1.5×1-8, 1K 3×1.5-8 | 103–124 lbs (47–56 kg) | ||
| A60 | 2K 3×2-8 | 200 lbs (90 kg) | ||
| A70 | 2K 4×3-8 | 227 lbs (103 kg) | ||
| Shaft centerline height: 17.5″ (445 mm). CP dimension: 7.25″ (184 mm) | ||||
| Bearing housing ref: D1201. Adapter ref for 8″: DAF108 | ||||
| Group II | 2K | A05 | 2K 2×1LF-10, 2K 2×1-10A | 210 lbs (95 kg) |
| A50 | 2K 3×1.5-10A | 220 lbs (100 kg) | ||
| A60 | 2K 3×2-10A | 226 lbs (103 kg) | ||
| A70 | 2K 4×3-10, 2K 4×3-10H | 225–249 lbs (101–112 kg) | ||
| A80 | 2K 6×4-10, 2K 6×4-10H | 290 lbs (130 kg) | ||
| Shaft centerline height: 23.5″ (597 mm). CP dimension: 12.5″ (318 mm) | ||||
| Bearing housing ref: D2201. Adapter ref for 10″: DAH108, for 13″: DAS108 | ||||
| Adapter OEM #: DAH108 = DY21806ACP, DAS108 = DY21857ABP | ||||
| Group III | 3K | A20 | 3K 3×1.5LF-13 | 328 lbs (149 kg) |
| A30 | 3K 3×1.5-13 | 250 lbs (112 kg) | ||
| A40 | 3K 3×2-13, 3K 4×3-13, 3K 4×3-13HH | 250–281 lbs (112–126 kg) | ||
| A80–A120 | 3K 6×4-16, 3K 8×6-16, 3K 10×8-16, 3K 10×8-17 | 641–992 lbs (291–450 kg) | ||
| Shaft centerline height: 33.875″ (860 mm). CP dimension: 18.75″ (476 mm) | ||||
| Bearing housing ref: D3201. Adapter ref for Group III: DNA108 (14″), DNE108 (16″) | ||||
| Adapter OEM #: DNA108 = DY28285ACP, DNE108 = DY27463ACP | ||||
Material Selection Guide for Durco Mark III Replacement Parts
Choosing the correct material for your replacement parts is critical for pump longevity and process safety. We cast and machine the following alloy families in-house, with full PMI verification and EN 10204 3.1 material certification:
| Material | ASTM Grade | UNS Number | Best For | Temp Limit |
|---|---|---|---|---|
| 316 Stainless Steel | CF8M (A743) | J92900 | General chemical processing, food-grade, mild corrosives | 700°F (371°C) |
| Carbon Steel | WCB (A216) | J03002 | Non-corrosive industrial service, water, oil | 800°F (427°C) |
| Duplex SS (CD4MCu) | 1B (A890) | J93372 | Chloride environments, seawater, sulfuric acid, phosphoric acid | 600°F (316°C) |
| Alloy 20 | CN7M (A743) | N08007 | Sulfuric acid service, pickling baths, stress-corrosion resistance | 800°F (427°C) |
| Monel 400 | M35-1 (A494) | N04400 | Hydrofluoric acid, seawater, alkaline environments | 800°F (427°C) |
| Nickel 200 | CZ-100 (A494) | N02200 | Concentrated caustic soda, high-temperature alkaline service | 700°F (371°C) |
| Hastelloy C-276 | CW6M (A494) | N10276 | HCl, FeCl₃, wet chlorine, mixed acids — severe oxidizing environments | 700°F (371°C) |
| Hastelloy B | CW12MW (A494) | N10001 | Pure HCl, reducing environments | 700°F (371°C) |
| Titanium Grade 2 | C-3 (B367) | R50250 | Wet chlorine, hypochlorites, nitric acid, oxidizing chlorides | 700°F (371°C) |
OEM Part Number Cross-Reference — Quick Lookup
Below is a sampling of common Durco Mark III OEM part numbers with our aftermarket equivalents. For a complete cross-reference of your specific pump model, submit your parts list.
| Component | Group | OEM Part Number | Our Reference |
|---|---|---|---|
| Shaft — Group I | Group I | CY50686A (sleeved), CY50683A | D1105S / D1105 |
| Shaft — Group II | Group II | CY32768B, CY21361BA | D2105 / D2105S |
| Shaft — Group III | Group III | CY50467A, CY50463A | D3105 / D3105S |
| Shaft Sleeve — Group I | Group I | AY50691A, AY38913AA, BY39477A | D1177 |
| Shaft Sleeve — Group II | Group II | — | D2177 |
| Shaft Sleeve — Group III | Group III | — | D3177 |
| Bearing Housing — Group I | Group I | CY55739AP | D1201 |
| Bearing Housing — Group II | Group II | CY55742AP | D2201 |
| Bearing Housing — Group III | Group III | DY55743AP | D3201 |
| Frame — Group I | Group I | DY55721B | D1119 |
| Frame — Group II | Group II | DY55718A | D2119 |
| Frame — Group III | Group III | DY55723A | D3119 |
| Adapter — Group II, 8″ | Group II | DY46074AAP | DAF108 |
| Adapter — Group II, 10″ | Group II | DY21806ACP | DAH108 |
| Adapter — Group II, 13″ | Group II | DY21857ABP | DAS108 |
| Adapter — Group III, 14″ | Group III | DY28285ACP | DNA108 |
| Adapter — Group III, 16″ | Group III | DY27463ACP | DNE108 |
Quality Assurance — How We Guarantee Fit
Every replacement part we ship undergoes a rigorous quality control process designed to eliminate the #1 concern with aftermarket pump parts: dimensional mismatch leading to unplanned downtime.
- CMM (Coordinate Measuring Machine) inspection — all critical mounting dimensions verified against OEM specifications with micron-level accuracy.
- Dynamic balance testing — every impeller balanced to ISO 1940 G6.3 or better, ensuring smooth operation and extended bearing life.
- Hydrostatic pressure testing — every casing tested at 1.5× rated pressure before shipment.
- 100% fit-testing — components are trial-assembled on reference fixtures or gauge plates to verify interchangeability.
- PMI (Positive Material Identification) — every alloy part verified for correct chemical composition using XRF analysis.
- EN 10204 3.1 MTR — full traceability from raw material heat number to finished part.
Ready to order? Send us your POS codes and quantities — we’ll provide pricing within 48 hours.
Disclaimer: Durco® and Mark III are registered trademarks of Flowserve Corporation. ANSI Pumps Pro is an independent aftermarket manufacturer. POS codes and OEM part numbers are used for cross-reference identification purposes only.