CC491K (RG5) Bronze Gland Followers for Centrifugal-Pump Stuffing Boxes
A CC491K (RG5) bronze gland follower should be purchased as a drawing-defined packing-compression component. Confirm the alloy designation, follower face and pilot geometry, clearance around the rotating sleeve, and usable adjustment travel. Matching the shaft diameter alone does not establish a usable replacement or an acceptable seal.
Start with the grade and the sealing function
BÖGRA’s RG5 material sheet identifies its material as CuSn5Zn5Pb5-C, CC491K, against DIN EN 1982:2008. This is a traceable designation for that sheet; a purchase order should state the required standard and edition, manufacturing route and certificate requirements. An informal “RG5” description is insufficient evidence for substituting an American alloy or an RG7 component.[1]
The follower pushes packing axially into the stuffing box. KSB explains that this compression generates radial contact against the shaft or sleeve and the box wall. Tightening therefore changes sealing contact and friction together; packing leakage can carry away frictional heat. The pump and packing instructions must define the adjustment and leakage requirements.[2]
Scope: this is an engineering guide for a possible custom gland-follower enquiry, not a claim that BONIU lists this part, holds CC491K stock, or supplies a certified pressure-containing assembly. A follower is not a substitute for the pump’s radial bearing.
Compare the dimensions by what they control
| Drawing feature | What it controls | Evidence to request |
|---|---|---|
| Bore around the sleeve | Non-contact running space under runout, assembly offset and operating movement | Sleeve envelope, concentricity references and specified installed clearance |
| Packing-contact face | How axial compression is delivered around the ring | Face geometry, flatness/parallelism requirements and burr control |
| Pilot and stuffing-box entry | Guidance without binding or unwanted contact | Pilot diameter/length, box bore and thermal-condition review |
| Bolt holes or slots | Assembly location and available adjustment | Bolt centres, slot length, washer seating and tool access |
| Follower nose and flange thickness | Packing engagement, remaining travel and structural section | Section drawing with packed, adjusted and limiting positions |
| Split joint, if specified | Assembly around an existing shaft and continuity of the loaded face | Matched-half identification, joint geometry and assembly method |
Do not derive the bore from a bronze-bearing clearance table: this follower is intended to remain clear of the rotating sleeve. Equally, an external pilot that fits a cold box does not prove that the nose has enough travel to compress the installed packing.
Check travel and tilt before changing material
Application analysis: construct an axial stack from the box shoulder to the packing face, follower nose, flange, washers and fasteners. Record the packing supplier’s initial stack requirement and the adjustment space the pump design permits. Check that a shoulder, flange or nut does not reach a mechanical stop before the required compression is achieved. Reproduce the actual arrangement rather than assuming that every pump uses the same number of rings or a lantern ring.
A second useful check is the follower’s position at two opposing, defined reference points. In an illustrative setup, readings differing by 0.4 mm over an 80 mm span represent atan(0.4/80), approximately 0.286° of geometric tilt. These assumed dimensions illustrate measurement sensitivity; they are not an allowable tilt, a tightening instruction or a calculation of packing pressure.
Unequal readings may arise from uneven packing seating, asymmetric adjustment or a damaged reference surface. Investigate the cause before compensating with bolt torque. A bronze grade change cannot correct a bottomed-out follower, a bent flange or an incorrectly seated packing stack.
Define service limits at assembly level
Select the alloy with the pump owner’s material requirements and the actual fluid, temperature, contamination and cleaning chemistry. CC491K is a lead-containing copper alloy; a familiar bronze name does not establish suitability for potable-water, food-contact or other restricted service. Require the applicable approval or a reviewed alternative where the service calls for one.
A supplier’s cast-bar strength or temperature statement is not a rating for a machined follower, its bolts, the stuffing box or the complete seal. Wall sections, bolt loading, casting quality and operating conditions require their own review. Do not infer pressure capability from the alloy designation.
Where leakage cannot be tolerated, stop and review the sealing arrangement with the pump and seal specialists. Tightening conventional packing until it appears dry is not a universal solution; KSB’s discussion makes clear that leakage and frictional heating are linked.[2]
Installation and adjustment checks
- Verify the drawing revision, alloy certificate where ordered, machined faces and split-half identity before assembly. Remove burrs without changing the specified contact geometry.
- Inspect the sleeve, stuffing-box bore and follower pilot for damage. Check the installed running space and freedom of movement using the pump’s approved procedure.
- Install the specified packing, ring arrangement and any flush components to the pump and packing suppliers’ instructions. This article supplies no generic ring count, bolt torque or leakage rate.
- Adjust the follower evenly using the approved sequence. Observe leakage, temperature and movement during controlled commissioning; retain the measured positions for later comparison.
- Use only the specified flush fluid, packing lubrication and fastener treatment. Grease intended for a bronze journal bearing is not automatically appropriate for a pump packing system.
Frequently asked questions
Is RG5 automatically interchangeable with C83600?
No. Obtain the specified standard, edition, composition limits, product form and required properties for both materials. BÖGRA’s CC491K identification does not authorize an unconditional cross-standard substitution.
Can I copy the worn follower?
Use it as inspection evidence alongside the approved drawing and mating dimensions. Wear, distortion or previous rework can make the old part an unreliable dimensional master.
Should the follower bore support the pump shaft?
Not in the non-contact follower arrangement discussed here. If the OEM drawing assigns another function to the component, that arrangement needs a separate review.
Can a new bronze follower eliminate all packing leakage?
The follower alone does not establish that outcome. Packing selection, sleeve condition, flush arrangement and the approved operating adjustment determine seal behaviour.
Technical sources
- BÖGRA: RG5 material data sheet, Rev.03. Manufacturer identification of RG5 / CuSn5Zn5Pb5-C / CC491K; not BONIU test data.
- KSB Centrifugal Pump Lexicon: Shaft seal. Packing-compression mechanism and the relationship between leakage, friction and heat.
Request a drawing review
Send the follower and stuffing-box sections, sleeve dimensions and runout information, bolt pattern, packing specification, required adjustment positions, fluid and temperatures, quantity, and required material documentation. Identify whether a split construction is required. Ask BONIU to review drawing feasibility and material availability; supply scope and acceptance requirements need written confirmation.