DN350 FIG3011 Parallel Slide Valve

Project Background

This report details the findings on a DN350 John Fig. 3011 Parallel Slide Valve, Arrangement Drawing:
AK332; which was received from LYB Operations & Maintenance for Inspection, Report and Repair.

Scope of Work

• Preliminary visual inspection on overall condition of the valve components.
• Perform a cleaning operation of the seating areas to remove scale and to properly allow assessment of the sealing faces and any other areas of concern.
• Post cleaning detailed inspection conducted.
• Dimensional check of stem and other major components for indication of wear.
• Details of recommended component replacement or repair.

Inspection & Procedure

Visual inspection of external and internal valve components.
Cleaning of seating surfaces to remove scale and debris.
Dimensional verification of critical components such as the stem, body seat, and discs.
Assessment of wear patterns, corrosion, and mechanical damage.
Recommendations for repair, refurbishment, or replacement of parts.

Conclusion & Recommendation

1. Visual Inspection (Preliminary):

Valve received in a heavily scaled and contaminated condition.
External coating showed signs of weathering; no structural cracks or deformation were noted.
Flange faces exhibited minor surface rust, likely due to storage conditions.

2. Internal Inspection (Post-Dismantling):

Significant scale buildup observed on the seating faces and body internals.
Valve discs showed uneven wear, particularly on the sealing edges.
Stem threads were intact but exhibited moderate wear and galling at the contact zones.
Bonnet gasket area had traces of prior leakage, indicating possible sealing failure.

3. Dimensional Checks:

Stem diameter measured against original drawing (AK332); slight reduction noted due to wear.
Disc and seat tolerances exceeded acceptable wear limits per manufacturer specs.
Guide slots and yoke bore were within acceptable tolerances.

Outcome

The valve body is structurally sound and suitable for continued use after internal refurbishment.
Discs require resurfacing or replacement due to excessive wear.
Stem recommended for replacement due to wear-related performance risks.
Reconditioning of the seat area is necessary to ensure reliable sealing.
Full cleaning and reassembly with new gaskets and fasteners are advised.

John Valves provided a full repair quote and lead time to the client. The client approved the refurbishment process based on the inspection findings. The valve was successfully restored to operational condition and reinstalled within the client’s processing facility.

Before:

After:

DN350 FIG3011 Parallel Slide Valve

DN600 Dam Needle Regulating Valve