SCR surge voltage rating
SCRs have both repetitive peak voltage ratings and non-repetitive peak voltage ratings. The non-repetitive ratings are higher, but probably not 3X; sometimes 2X and sometimes only 1.1X. If that is important for some particular application, you will need to look at spec sheets.

Semiconductor current ratings are based on maintaining the temperature of the junction at a safe level. The mass of the case and any mandatory heatsink stores thermal energy during a current surge insuring some safety margin in the event of a momentary increase in current.

There is very little in the physics of a semiconductor to preventing it from being destroyed by a momentary increase in voltage stress. The limits that are stated are hard limits. Since SCR application voltages are usually dependent on variation in the utility voltage supply, the peak voltages that they encounter are not reliably predictable. Circuit designs can protect the device to an extent with transient-suppression measures. As a result, the practice that is usually followed is to select a device with a peak repetitive voltage rating that is about twice the peak voltage that is routinely expected in the application.

There are no basic rules about peak voltages. The reason is probably pretty deep into the details of the design physics of the device. There are design variations to make SCRs more suited to forced commutation and high frequency vs. natural commutation and utility frequency. There may be some other design variations that are not so easily classified.