Do H2B visa holders pay social security tax? Can they be refunded for social security tax since they have no access to these public funds as pension etc?

Yes, you MUST pay Social Security and Medicare taxes.

No, you will NOT get a refund.

Yes, I know it is unfair, but that is the current law.

Now, it is possible that your home country and the U.S. have completed a totalization agreement, which will allow your tax payments to be credited under your home country's social security system.