Valve Live Loading With Belleville Springs. Belleville Springs for Valve Live Loading

Transcription

1 Valve Live Loading With Belleville Springs

2 What is Valve Live Loading? The addition of Belleville Springs to the gland follower studs to maintain the packing load of the valve over time.

3 What s In The Name? Belleville Named for Julian F. Belleville who received a British patent in the 1860 s. (It was on a valve application) Belleville Springs, Belleville Disc Springs, Disc Springs and Conical Compression Washers are all names for the same type of spring.

4 Typical Belleville Spring OD h ID H Comprised of 5 main components Outside Diameter Inside Diameter Material Thickness Overall Height Deflection or Movement

5 Single Belleville Spring 1500 lb. Flat Load (Example)

6 Belleville Spring with 1500lb/689kg Flat Load No Load 33% 66% Flat 0lbs/0kg 500lbs/227kg 1000lbs/454kg 1500lbs/680kg

7 Stacking Arrangements of Solon Belleville Springs Single Parallel Series Parallel / Series

8 Deflection Chart Load Deflection

9 Which Valves Are Candidates For Live Loading? Frequently Cycled Valves Operated Valves (Air or Motor) Critical Applications Safety or Difficult Location History of Packing Leaks Monitored Valves

10 Reasons For Valve Leaks? Wrong Packing for the Application Bent, Scored, or Pitted Valve Stems Improper Packing Installation Infrequent Use Frequent or High Cycles Loss Of Packing Load

11 How Live Loading Works Packing Compressive Stress (PSI) With Live Load Without Live Load Packing Compressive Stress (MPa) In - Service Consolidation (%)

12 Retightening Vs Live Loading Packing Pressure Leakage Threshold Years 1 2 No Live Load Gland Nuts Re-tightened Loss Of Torque Leads To Leakage Live Load Springs Maintain Packing Pressure

13 Basic Formula For Calculating A = Packing Area Valve Live Loading Required Bolt Load = A x P P = 1.5 x System Pressure or Manufacturers Load Factor (Whichever is greater) B = Number of Gland Bolts B Torque (Ft. Lbs.) =.2 x Bolt Load x Bolt Diameter 12 Formula based on 5 ring graphite set (EPRI)

14 Selecting the Proper Spring Material Operating Environment & Temperature 17-7PH Most Widely Used Good for most environments except Chloride & Fluorides (Unless plated) -400 F / -240 C to 550 F / 288 C 301 SS Limited Size Range -400ºF/-240ºC to 550ºF/288ºC Inconel 718 Higher Cost High Temperatures & Corrosives -400F / -240C to 1100F / 593 C 6150 Alloy Needs to be plated for outdoor use -40ºF/-40ºC to 350ºF/177ºC H-13 Tool Steel High Temp Ambient to 1100F / 593C

15 Selecting the Proper Spring Material Spring Load vs Material It is important to note when selecting a Belleville spring that the same size part made with a different material may have a different flat load.

16 Factors in Selecting a Belleville Spring Material Temperature Environment Corrosives Coatings Size Constraints OD, ID, Height of spring stack Load Usually select a spring with a flat load 20% higher than the preload

17 Typical Installation of Solon Belleville Springs

18 Alternate Installations

19 Alternate Installations

20 Alternate Installations

21 Sleeves No Sleeves

22 Why Sleeves Are Used I.D. Of Spring Is Too Large For The Gland Stud Metric Springs Used With Inch Studs Sleeve Is Used To Limit Torque Spring Thickness Is Less Than The Stud Thread Root Sleeve Is Used To Measure Relaxation In Packing (Usually Done With External Sleeve)

23 Other Live Loaded Areas Live Loaded Bonnet Belleville Spring

24 Other Live Loaded Areas Live Loaded Ball Seat Belleville Spring

25 Typical Live Loading Survey Sheet Live Loading Information Stem Dia. * Stuffing Box Dia. * Stuffing Box Depth* Stud Dia. * No. of Studs* System Temp. * System Pressure* Packing Type* Available Stud Length No. of Packing Rings Packing Load Packing Torque In-Service Consolidation Bushing Hgt * Req d For Live Loading Calculations Spring Information Solon Part No. No of Springs / Stud Spring Configuration Bonnet Information No. of Studs Stud Dia. Gasket Type Gasket Size Gasket No. Torque Solon Part No. General Information Customer Unit System Valve Mfg. Valve Size Valve Class Valve Type Serial No. Tag No. Location Position Operated Flange Information No. of Studs Stud Dia. Gasket Type Gasket Size Gasket No. Torque Solon Part No.

26 Thank you! Solon Manufacturing Co. George Davet, Chief Engineer OD h ID H