All Category - Hubbard Ground Expansion Plugs - Metric Sizes to DIN 470

Metric Sizes to DIN 470

  • The ground expansion plug offers the greatest level of holding power or leak resistance available in an expansion plug.
  • The ground edge provides maximum contact surface area and finest surface finish.
  • To maximize effect, the counter bore should receive special finishing.
  • Ground Plugs, installed in a correctly prepared counter bore, should eliminate the need for sealer and should hold highly penetrating liquids.
  • While their cost is higher than standard Hubbard Plugs, they are less expensive than pipe plugs or other closures when considering the total cost including tapping.
  • We grind the edge circumferentially to a high finish, and segregate the parts when packing to prevent damage to the edge during shipment. For greatest protection ground edge Hubbard Plugs should be kept in their packing containers up to the point of assembly.
  • We have found 1” diameter .083” thick steel ground plugs to hold 1,600 lbs of pressure before failure, which is between 10 and 20 times the holding power of a standard blanked edge plugs. The effective use range should be less than that.

Stock Materials:

  • Steel: SAE1008/1010 low carbon steel: ASTM#A109 or A569 depending on gage.
  • Stainless Steel: 302 / 304 ASTM#A313
  • Brass: ASTM#B36.
* These are materials we stock in various thicknesses. It does not mean we have finished inventory of all plugs in each of these materials.
** Customer specific materials different than those listed above are commonly run.


  • All ground plugs are packaged in segregated rows with a special light oil finish.

Item #
Nominal Diameter 'A'
Maximum Diameter Limit
Minimum Diameter Limit
Spherical Radius
Note : click on item number to submit request for quote
HPMG-630 1616.0715.9322
HPMG-709 1818.0717.9325
HPMG-787 2020.8719.9328
HPMG-866 2222.0721.9330
HPMG-984 2525.0724.9334
HPMG-1102 2828.0727.9340
HPMG-1260 3232.0731.8745
HPMG-1417 3636.0735.8750
HPMG-1575 4040.1339.8756
HPMG-1772 4545.1344.8763
HPMG-1969 5050.1349.8770
HPMG-2205 5656.1355.8780
HPMG-2480 6363.1362.8790
Total: 13