API St 622 pdf download Type Testing of Process Valve Packing for Fugitive Emissions
6 Packing Materials Test
The packing materials test considers weight loss, density, lubricant content, and leachables as per the proceduresoutlined below.For new configurations, test packing shall be selected at random from a minimum production lot assupplied by the manufacturer. For existing configurations, test packing shall be provided by a blind selection ofproduction product from the manufacturer’s normal distribution network. Validation of the random or the blindselection of process shall be provided to the testing lab.Random selection does not apply to testing of prototypematerial.
6.1weight Loss Testing
6.1.1 Graphite Foil weight Loss Test Procedure
Weight loss of graphite packing rings shall be determined as follows.
a) Conducted in a controlled environment using suitable testing equipment.
b) Flexible graphite sample size shall be between 0.5 grams and 3.5 grams.
c) Three samples shall be tested. Record weight of each sample.
d) Samples shall be preconditioned for one hour at 150 °C(302 °F) with a ramp up speed of 10 “C(18*F)perminute.Record dried sample weight and use for weight loss percentage calculations.
e)After one hour, the samples shall continue ramping up at 10 “℃(18 °F) per minute to the final test temperatureof 593C (1100″F)±2c(3.6RF).
f) This test temperature shall be held for 24 hours and then cooled.g) weigh samples after cooling and record weight.
NOTE TGA testers have the capablity to weigh samples without being removed from the heat souroe. This is anacceptable altenative to cooling and weighing.
h) Determine the percent weight loss of each sample and record.
i) Average the results and a weight loss greater than 15 % is not acceptable.
NOTE This test method also follows an established testing standard,FSA-G-604-07 Method B, issued by the FltuidSealing Association.
6.1.2 Braided Packing Ring Weight Loss Test ProcedureWeight loss of braided packing rings shall be determined as follows.
a) Conducted in an oven with full exposure to air (Oxygen-rich environment).
b) Select three test rings of a sample packing set. If the packing set is comprised of more than one type of
packing ring, each type shall be tested.
c) Record weight.
d) Preheat oven to 150 °C (300°F).
e)Place sample in oven for one hour.
fyRemove samples, cool to room temperature, and record weight.
g) lIncrease oven temperature to 260 °C(500 °F) and repeat step e and step f.
h) Increase temperature to 538 C in 56 °C (1000 “F in 100 °F) increments, repeating step e and step f after
i) Discontinue test if weight loss exceeds 50 %.6.2Density
Packing Density shall be determined by dividing the sample weight by the sample volume, with the sample volumedetermined as follows:
a)Braided packing volume shall be determined by measuring the sample length, width and thickness.
Volume = Median Length x Width x Thickness
b) Die-formed packing (ring form) volume shall be determined by the following equation:
Volume =[(Ring OD2- Ring ID2)x Ring Thickness ×N] /4
oD is the outside diameter;IDis the inside diameter.
6.3.1 Polytetrafluoroethylene(PTFE) Content
PTFE content shall be established by determining the percentage total fluorine in the packing, and comparing with abase fluorine percentage of 76, as follows:
a) determine total percent of fluorine content using ASTM D1179 or ASTM D4327, and
b) divide total percent of fluorine as obtained in a) by 0.76 to obtain the approximate percent of PTFE content.6.3.2 Wet Lubricant
Wet lubricant percentage shall be determined by dividing the “-weight of the lubricant extract” by the “”original sampleweight” and multiplying by 100.The procedure shall be as follows.
a) Cut samples into short lengths, and record the total sample weight (approximately 15 grams is required).b) Place cut samples into an extraction thimble and insert thimble into Soxhlet extraction unit that is nearly filledwith a solvent,such as methylene chloride.
c) Turn on water flow through the condenser and bring the methylene chloride to a moderate boil through the
use of the “low” setting on a hot plate.Extract for approximately 16 hours.