01 Jan 2026

RongshengHBRS 2FZ35-35 Shear BOP-2

Core Compatibility & Operational Context

Target Equipment: Rongsheng Machinery (Huabei Oilfield) BOP Stacks utilizing the S-Type Ram Profile.
Primary Function: The S-Type Ram Assembly is engineered to provide a reliable hydraulic seal against various drill string diameters. Unlike standard rams, the "S-Type" designation often refers to a specific contouring or sealing mechanism designed to handle high-pressure differentials and non-standard pipe profiles.
User Imperative: For drilling engineers and maintenance supervisors, selecting the correct part number is critical. Using mismatched seals or blocks can result in seal failure, leading to well control issues. This guide details the specific F751.xx part family required for these assemblies.

1. Ram Block Components (The Structural Core)

Technical Context & Value Proposition
The Ram Block is the steel skeleton of the assembly. It transmits the hydraulic force from the piston to the sealing elements and provides the structure that supports the pipe once sealed. In high-torque drilling scenarios, the integrity of the block and its connection to the operating rod is paramount.

#	Part Description	Part Number	Material Specification	Failure Analysis & Prevention
1	Ram Block	F751.14.24.01	Alloy Steel (Typically 4140/4340)	Cause: Bore erosion due to high-velocity fluid bypass. Prevention: Ensure the front seal is intact; never leave rams partially closed on pipe for extended periods.
2	Holder	F751.14.24.03.00	Forged Carbon Steel	Cause: Shear pin failure or deformation. Prevention: Inspect for hairline cracks during NDT (Non-Destructive Testing); these are high-stress concentration points.
3	Ram Screw	F751.14.24.04.03	High Tensile Steel	Cause: Thread galling or loosening. Prevention: Use anti-seize compound on threads and verify torque specifications (typically per API 16A).
4	Screw (M12x60)	GB70-85	Stainless Steel 35	Cause: Vibration-induced loosening leading to component drop. Prevention: Use thread-locking adhesives or lock wire where permissible.

2. Sealing Elements (The Pressure Barrier)

Technical Context & Value Proposition
The Sealing Element (often a rubber boot or packing unit) is the consumable component that directly contacts the drill pipe. In the S-Type assembly, these elements are designed to extrude slightly under pressure to fill the annular space, creating a dynamic seal that holds pressure from either direction (below or above the rams).

#	Part Description	Part Number	Material Specification	Failure Analysis & Prevention
1	Sealing Element	F751.14.24.02.00	Nitrile Rubber (NBR) / HNBR	Cause: Extrusion gap failure; the rubber is literally squeezed out of the metal housing. Prevention: Measure the clearance gap between the ram face and the housing dovetail; if oversized, replace the metal parts.
2	Sealing Element	F751.14.04.09.02.00	Elastomer Compound	Cause: Thermal degradation from high-temperature wells. Prevention: For wells exceeding 100°C, consider upgrading to Hydrogenated Nitrile (HNBR) or Fluoroelastomer (FKM).
3	Sealing Element	F751.14.04.01.02.00	Rubber Compound	Cause: Swelling due to incompatible oil-based muds (OBM). Prevention: Ensure the compound is certified for OBM exposure to prevent loss of durometer (hardness).
4	Sealing Element	F751.14.04.02.02.00	Rubber Compound	Cause: Brittle fracture in cold environments. Prevention: In arctic or deepwater applications, verify the low-temperature brittleness rating of the elastomer.
5	Sealing Element	F751.14.04.03.02.00	Rubber Compound	Cause: Abrasive wear from cuttings. Prevention: Regularly clean the BOP cavity; sand is the primary enemy of rubber seals.

3. Complete Ram Assemblies (Pre-Configured Units)

Technical Context & Value Proposition
These part numbers represent the fully assembled unit, ready for installation into the BOP body. Using a complete assembly reduces downtime during BOP stack changes. The "Variable" designation indicates a variable bore ram (VBR) capable of sealing against a range of pipe diameters.

#	Part Description	Part Number	Size / Specification	Failure Analysis & Prevention
1	Assembly	F751.14.24.00	2 3/8"	Cause: Piston O-ring leakage preventing full closure. Prevention: Test the ram function with low oil pressure first to check for smooth operation.
2	Assembly	F751.14.04.09.00	2 7/8"	Cause: Latch mechanism failure. Prevention: Inspect the locking mechanism that holds the ram in the open position.
3	Assembly	F751.14.04.01.00	3 1/2"	Cause: Hydraulic fluid contamination scoring the piston bore. Prevention: Maintain hydraulic fluid cleanliness (ISO 4406 standards).
4	Assembly	F751.14.04.02.00	4 1/2"	Cause: Misalignment causing cocking of the ram. Prevention: Ensure the ram guide pins and bushings are not worn.
5	Assembly	F751.14.04.03.00	5"	Cause: Corrosion of internal steel components. Prevention: Apply corrosion inhibitors during storage and operation.
6	Assembly	F751.14.04.04.00	5 1/2"	Cause: Fatigue cracking in the linkage. Prevention: Perform magnetic particle inspection (MPI) on high-cycle units.
7	Assembly	F751.14.04.05.00	7"	Cause: Excessive friction. Prevention: Lubricate all sliding surfaces with molybdenum disulfide (Moly) grease.
8	Assembly	F751.14.04.06.00	9 5/8"	Cause: Incomplete closure due to debris. Prevention: Utilize a "wiper" tool to clean the BOP bore before running the string.
9	Assembly	F751.14.04.08.00	5" - 5 1/2" Variable	Cause: Poor seal on extreme sizes. Prevention: Variable Bore Rams (VBRs) have limitations; they seal best near the middle of their range. Avoid using them at the absolute min/max limits if possible.

Strategic Sourcing Recommendation

Maintaining the integrity of your Rongsheng BOP stack is a non-negotiable aspect of well safety. To minimize non-productive time (NPT) during critical maintenance windows, we advise verifying your inventory against the specific F751.xx part numbers listed above. Due to the specificity of the S-Type profile, standard ram blocks may not fit or function correctly. Please ensure your procurement team sources components that meet API 16A specifications to guarantee compatibility and pressure integrity.

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