CAMTOP 20-3/4″ 3M psi Bolted-Cover Spherical BOP, API 16A / 16D Class PR1, forged alloy steel body with replaceable wear bands & adapter ring wear band – full 26-part maintenance BOM with P/N list + optional Seal Kit 156527 / Accumulator Kit 152717 provided.
CAMTOP 20-3/4″ 3M Spherical BOP | Bolted-Cover API 16A | 26-Part Core BOM | CAMTOP
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Description
1. Product Overview
The CAMTOP 20-3/4″ 3M psi Bolted-Cover Spherical BOP is the largest-bore member of our API 16A Class bolted-cover spherical BOP family. Designed for the largest surface casing strings, conductor strings, and high-capacity drilling rigs, this 20-3/4″ bore (527 mm) BOP delivers 3,000 psi working pressure on a forged alloy-steel body with replaceable wear bands and the original CAMTOP dual-packer sealing system.
CAMTOP’s Bolted-Cover Spherical BOPs (also known as “spherical preventers” or “mud line BOPs”) combine a hinged spherical body that rotates to open or close on the drill string with a bolted cover for fast field rebuild access. The cover is held by a circle of B7 studbolts and 2H nuts – the same principle used on Cameron-style and Shaffer-style spherical BOPs found on jack-up rigs and large onshore drilling platforms worldwide.
This page also includes CAMTOP’s complete 26-part core maintenance BOM (Bill of Materials) plus the optional Seal Kit 156527 (which includes all recommended spare seals) and Accumulator Kit 152717 (non-standard) — the same parts list we issue with our refurbishment kits.
2. Product Image

3. Key Features
- 20-3/4″ (527 mm) Large-Bore Design — the largest bore in CAMTOP’s bolted-cover spherical BOP family, sized for 20″ conductor strings and surface casing.
- 3,000 psi (3M) Working Pressure — API 16A Class PR1, ideal for conductor-pipe and surface-casing pressure control on land rigs and large jack-ups.
- Bolted-Cover Construction — covers secured by 24× B7 studbolts and 2H nuts provide fast field-rebuild access without specialized hydraulic tools.
- Forged Alloy-Steel Body — ASTM A4130 / A4140 low-alloy forged steel, normalized and tempered per API 16A.
- Dual-Packer Sealing System — interchangeable nitrile (blue, standard) and natural (red, high-temp) elastomer packers seal on open hole, on pipe, or on closed blind.
- Replaceable Wear Bands — top adapter-ring wear band and piston wear rings (P/N 150613 family) reduce erosion on sealing surfaces, increasing service life.
- API 6A Studded End Connections — top and bottom flanges conform to API 6A / 16A flange specifications for direct wellhead-bowl integration.
- Sour-Service (NACE MR0175) Compatible — elastomers, seals, and trim materials available in NACE MR0175 sour H₂S configuration.
- Optional Seal Kit 156527 — pre-packaged set of all recommended spare seals for fast field rebuild during rig downtime.
- Optional Accumulator Kit 152717 — pre-engineered accumulator pre-charge assembly (non-standard accessory for fast BOP-loop commissioning).
4. Technical Specifications
| Parameter | Specification | CAMTOP / Industry Standard |
|---|---|---|
| Bore Size | 20-3/4″ (527 mm) | Largest bore in bolted-cover spherical family |
| Working Pressure | 3,000 psi (20.7 MPa) | API 16A Class PR1 |
| Test Pressure | 1.5× WP = 4,500 psi hydrostatic | API 16A / 16D hydrostatic test |
| API Material Class | Class AA / BB / CC / DD / EE | Per API 6A material classification |
| Performance Class | PR1 | API 16D performance |
| Temperature Class | T-21 (Class B, -29 °C to +121 °C) | Low-temp carbon / alloy steel |
| Body Material | Forged alloy steel ASTM A4130 / A4140 | Normalized & tempered, ultrasonic-tested |
| Cover Bolts | B7 studbolts × 2H nuts, 24× around cover | ASTM A193 B7 / A194 2H |
| Elastomer Material | Nitrile (blue) standard; Natural (red) high-temp | H₂S / NACE MR0175 optional |
| Replaceable Wear Bands | Piston wear rings × 3; Adapter-ring wear band × 1 | Extends BOP service life |
| End Connection | API 6A studded flange (top & bottom) | API 6A / 16A flange standard |
| Operation | Hydraulic actuator (separate unit) | 3000 psi hydraulic supply standard |
| Hydraulic Operating Pressure | 1,500 – 3,000 psi | Standard rig accumulator charge |
| Approx. Weight | ~12,500 kg (27,500 lb) | Heavy-duty forged construction |
| Approx. Height | 2,032 mm (80″) | Spherical cavity included |
| Operating Temperature | -29 °C to +121 °C (-20 °F to +250 °F) | API 16A Class B |
| Coating | Red epoxy (RAL 3000) marine-grade | Salt-water and offshore-rated |
| Standard Sour Trim | NACE MR0175 compliant | Sour-service H₂S available |
| Optional Seal Kit | P/N 156527 — full set of recommended spare seals | *Not a standard accessory |
| Optional Accumulator Kit | P/N 152717 — pre-charge assembly (non-standard) | †Not a standard accessory |
5. Component Breakdown & Construction (Figure 4-13 Exploded View)
The diagram below shows the complete CAMTOP Bolted-Cover Spherical BOP exploded view, with all replaceable component groups called out for maintenance reference.

| Callout | Component | Function |
|---|---|---|
| ① | Nut for Top API Flange | Secures top flange to upper housing |
| ② | Stud for Top API Flange | High-tensile threaded stud for top flange |
| ③ | Nut (cover) | Secures bolted cover to upper housing |
| ④ | Stud (cover) | High-tensile stud holding cover in place |
| ⑤ | Anchor Shackle | Lifting eye for rig hoisting / BOP handling |
| ⑥ | Upper Housing, Studded | Top forging — accepts cover flange & pivots shut |
| ⑦ | Sealing Element (packer) | Nitrile (blue) or Natural (red) elastomer |
| ⑧ | Seal, Adapter O.D. (5) | Outer-diameter seal between adapter ring & body |
| ⑨ | Seal, Adapter Top (C) | Top-face seal of adapter ring |
| ⑩ | Adapter Ring* | Wear-resistant inner sleeve (with optional wear band) |
| ⑪ | Seal, Adapter I.D. Upper (B) | Upper inner-diameter seal of adapter |
| ⑫ | Seal, Adapter I.D. Lower (4) | Lower inner-diameter seal of adapter |
| ⑬ | Piston | Moves sealing element up/down to close on pipe |
| ⑭ | Wear Band | Replaceable wear surface (top & bottom of piston) |
| ⑮ | Seal, Piston O.D. Upper (3) and Lower (1) | Outer piston seals (top & bottom) |
| ⑯ | Seal, Piston I.D. Upper (A) | Upper piston inner-diameter seal |
| ⑰ | Seal, Piston I.D. Lower (2) | Lower piston inner-diameter seal |
| ⑱ | Wear Band | Replaceable wear surface (additional) |
| ⑲ | Lower Housing, Flanged | Bottom forging — accepts inlet flow & pivots shut |
| ⑳ | Pipe Plug | Seals hydraulic-port / bleed-off port |
* Note: Some bolted-cover sphericals have a wear band on the adapter ring. This wear band is not shown on Figure 4-13.
6. Bill of Materials (26-Part Core BOM + Optional Kits)
Below is CAMTOP’s complete 26-part core maintenance BOM for the 20-3/4″ 3M psi Bolted-Cover Spherical BOP. All P/Ns are stocked and ready for immediate spare-part dispatch. The two optional kits at the bottom of the list are non-standard accessories — Seal Kit 156527 includes all recommended spare seals, and Accumulator Kit 152717 is a pre-charge assembly used during commissioning.
6.1 Main Body Parts (typical)

6.2 Piston / Seals / Fasteners / Wear Rings (continued)

6.3 Full Bill of Materials — HTML Reference Table
| Item | Description | P/N | Qty. | Notes |
|---|---|---|---|---|
| 1 | Lower Housing-Flanged | 156512 | 1 | Main forging – bottom |
| 2 | Upper Housing-Studded | 156513 | 1 | Main forging – top |
| 3 | Piston | 156523 | 1 | Vertical sliding sealing element carrier |
| 4 | Adapter Ring | 156521 | 1 | Inner sealing sleeve |
| 5 | Nitrile (Blue) | 150799 | 1 | Standard elastomer packer – blue |
| 6 | Natural (Red) | 150800 | 1 | High-temperature elastomer packer – red |
| 7 | Stud | 156528 | 1 Set** | Cover studbolts |
| 8 | Nut | 020110 | 1 Set** | Cover 2H nuts |
| 9 | Seal-Piston I.D.-Upper | 031108 | 1 | P/N 031108 |
| 10 | Seal-Piston I.D.-Lower | 030761 | 1 | P/N 030761 |
| 11 | Seal-Piston O.D. | 031013 | 2 | Upper and lower |
| 12 | Seal-Adapter I.D.-Upper | 031107 | 1 | P/N 031107 |
| 13 | Seal-Adapter I.D.-Lower | 031018 | 1 | P/N 031018 |
| 14 | Seal-Adapter O.D. | 031031 | 1 | Outer sealing |
| 15 | Seal-Adapter Top | 031027 | 1 | Top-face sealing |
| 16 | Wear Ring-Piston | 150613 | 2 | Replaceable piston wear band |
| 17 | Wear Ring-Lower Housing | 150613 | 1 | Replaceable lower-housing wear band |
| 18 | Pipe Plug | 066329 | 2 | Port sealing plug |
| 19 | Anchor Shackle | 060498 | 2 | Lifting eye |
| 20 | Stud for API Flange | 011028 | 1 Set** | Top API flange stud |
| 21 | Nut for API Flange | 020015 | 1 Set** | Top API flange 2H nut |
| 22 | Wear Ring-Adapter Ring | 152344 | 1 | Replaceable adapter wear band |
| 23 | Eye Bolts | 050243 | 2 | Lifting bolts |
| 24 | Hammer Wrench | 050825 | 1 | Field-service tool for cover studs |
| 25 | Pipe Plug 1/2″ NPT | 066326 | 1 | Auxiliary port 1/2″ |
| 26 | Pipe Plug 1/4″ NPT | 065008 | 1 | Auxiliary port 1/4″ |
| Optional | Seal Kit* | 156527 | 1 | Not standard — includes all recommended spare seals |
| Optional | Accumulator Kit † | 152717 | 1 | Not standard — non-standard pre-charge assembly |
Reference size: 3 1/8″ per OEM BOM (Used for the spherical cavity trim / seal size reference dimension)
Ordering Tip: All 26 part numbers in this core BOM are stocked by CAMTOP for rapid spare-part dispatch. For a complete rebuild kit, order all parts above — typical rebuild requires replacement of the wear rings (150613 / 152344), piston & adapter seals (031108 / 030761 / 031013 / 031107 / 031018 / 031031 / 031027), and the elastomer packers (Nitrile 150799 / Natural 150800). Seal Kit 156527 conveniently bundles all of these seals for fast field rebuild.
7. How It Works
The CAMTOP Bolted-Cover Spherical BOP is a two-piece body with hinged spherical mating surfaces. A rotating operator (typically a hydraulic actuator on a separate skid, not shown) pivots the upper and lower housings together to close on the pipe or open the well bore. The bolted cover gives direct access to the spherical cavity and the dual-packer sealing system.
- Open Position: The two body halves are pivoted apart, leaving the full 20-3/4″ bore open for tripping drill pipe, casing strings, or wireline tools.
- Close on Pipe: The hydraulic actuator rotates the housings together with the sealing element wrapped around the drill pipe, sealing the annulus against any pressure kick.
- Close on Open Hole: With no drill pipe in the hole, the elastomer packer closes completely on itself, forming a full-bore pressure barrier.
- Wear-Band Function: The replaceable piston wear rings (P/N 150613) and adapter-ring wear band (P/N 152344) take abrasion from circulating mud, sand, and cuttings — protecting the more expensive inner seals and prolonging service intervals.
- Field Rebuild: Remove the bolted cover by backing off the 24 cover nuts (Item 8), then lift out the piston, elastomer packers, and wear rings. Replace seals and wear bands as required, then reassemble with new cover studs (Item 7). A hammer wrench (Item 24) is included.
8. Applications
- 20″ Conductor / Surface Casing Strings — the 20-3/4″ bore clears any standard surface casing OD up to 20″.
- Land Rigs & Large Jack-Up Rigs — designed for deepwater and high-capacity land drilling operations.
- HPHT Surface Stack — the Class B temperature rating (-29 °C to +121 °C) covers conventional HPHT surface operations.
- Sour H2S Service (NACE MR0175) — optional sour trim for environments with H2S exposure.
- Drilling Spool Adapter — fits between the wellhead and the BOP stack as a primary or secondary barrier.
- Workover & Completion Operations — provides a redundant pressure barrier during wireline or coiled-tubing interventions.
- Well-Test Service — used in test trees on land and offshore platforms requiring large-bore pressure barriers.
- Snubbing Operations — frequently used during snubbing under pressure on stripper wells.
9. Why Choose CAMTOP
- API 16A / 16D Certified Factory — every CAMTOP BOP is hydrostatic-tested and traceable per API monogram requirements.
- Direct Factory Pricing — 30-50% below OEM replacement cost (Cameron, Shaffer, Hydril equivalent).
- 26-Part Core BOM Support — all 26 listed part numbers stocked for fast spare-part dispatch worldwide.
- Optional Seal Kit & Accumulator Kit — pre-packaged kits (Seal Kit 156527 / Accumulator Kit 152717) for fast field rebuild.
- 5-Year Spare-Part Guarantee — CAMTOP guarantees spare-part availability for the BOP family for a minimum of 5 years after delivery.
- Custom Bore & Pressure Available — OEM/ODM for custom bores (4-1/16″ through 21-1/4″) and pressures (2,000 psi through 15,000 psi).
- Global Logistics — FOB Shanghai, CIF Houston / Aberdeen / Dubai / Singapore — typical delivery in 7-10 working days.
10. Ordering Information
When ordering the CAMTOP 20-3/4″ 3M psi Bolted-Cover Spherical BOP or any spare part from the 26-part BOM, please specify:
- Model / SKU: CT-SPB-2034-3M-001 (main assembly)
- Bore size: 20-3/4″ (527 mm) — confirm required casing OD
- Working pressure: 3,000 psi (PR1)
- Material class: AA, BB, CC, DD, or EE
- Elastomer: Nitrile (Blue, standard) / Natural (Red, high-temp) / NACE MR0175 Sour H2S
- Optional accessories: Seal Kit 156527 and/or Accumulator Kit 152717
Contact CAMTOP for Orders & Technical Support
Email: sales@cposl.com
Phone: +86-18621723891
Address: Shanghai, China
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