| Adriatica Pipeline | Italy | Operating | Parent | 100% | 94 | 8.8 |
| Adriatica Pipeline | Italy | Under construction | Parent | 100% | 140 | 1.83 |
| Adriatica Pipeline | Italy | Operating | Parent | 100% | 195 | 8.8 |
| Adriatica Pipeline | Italy | Operating | Parent | 100% | 73 | 8.8 |
| Adriatica Pipeline | Italy | Proposed | Parent | 100% | 170 | 6.94 |
| Adriatica Pipeline | Italy | Proposed | Parent | 100% | 114 | 6.94 |
| Alessandria–Cortemaggiore Gas Pipeline | Italy | Operating | Parent | 100% | 118 | — |
| Alexandroupolis INGS Terminal Pipeline | Greece | Operating | Parent | 7.2% | 28 | 8.3 |
| Altamura–Candela Gas Pipeline | Italy | Operating | Parent | 100% | 110 | — |
| Altamura–Ferrandina Gas Pipeline | Italy | Operating | Parent | 100% | 30 | — |
| Altamura–Latiano Gas Pipeline | Italy | Operating | Parent | 100% | 144 | — |
| Altamura–Latiano Gas Pipeline | Italy | Operating | Parent | 100% | 144 | — |
| Ampelia–Bralos Gas Pipeline | Greece | Operating | Parent | 36.2% | 74 | — |
| Ampelia–Volvos Gas Pipeline | Greece | Operating | Parent | 36.2% | 50 | — |
| Austria–Slovenia Interconnector (SOL) Gas Pipeline | Austria, Slovenia | Operating | Parent | — | 28 | — |
| Benevento–Biccari Gas Pipeline | Italy | Operating | Parent | 100% | 53 | — |
| Bernalda-Brindisi Gas Pipeline | Italy | Operating | Parent | 100% | 112 | — |
| Bernalda–Grumento Gas Pipeline | Italy | Operating | Parent | 100% | 91 | — |
| Biccari–Candela Gas Pipeline | Italy | Operating | Parent | 100% | 36 | — |
| Biccari–Massafra Gas Pipeline | Italy | Operating | Parent | 100% | 195 | — |
| Bidirectional Austrian-Czech Interconnector Gas Pipeline (BACI) | Austria, Czechia | Shelved | Parent | — | 62 | 6.5 |
| Bralos–Aliartos Gas Pipeline | Greece | Operating | Parent | 36.2% | 95 | — |
| Buccino-Contrada-Melizzano Gas Pipeline | Italy | Operating | Parent | 100% | 138 | — |
| Calderari Enna–Gela Gas Pipeline | Italy | Operating | Parent | 100% | 67 | — |
| Caldonazzo-Trento Gas Pipeline | Italy | Operating | Parent | 100% | 17 | — |
| Camisano-Zimella Gas Pipeline | Italy | Operating | Parent | 100% | 41 | — |
| Campagna Lupia–Ravenna Gas Pipeline | Italy | Operating | Parent | 100% | 109 | — |
| Canicatti–Enna Gas Pipeline | Italy | Operating | Parent | 100% | 60 | — |
| Cavarzere-Minerbio Gas Pipeline | Italy | Operating | Parent | 100% | 83 | — |
| Celleno-Cetona Gas Pipeline | Italy | Operating | Parent | 100% | 59 | — |
| Celleno-Gallese Gas Pipeline | Italy | Operating | Parent | 100% | 35 | — |
| Cervignano-Rognano Gas Pipeline | Italy | Operating | Parent | 100% | 32 | — |
| Cervignano–Ripalta Gas Pipeline | Italy | Operating | Parent | 100% | 22 | — |
| Cetona-Terranuova Gas Pipeline | Italy | Operating | Parent | 100% | 76 | — |
| Chieti–San Salvo Gas Pipeline | Italy | Operating | Parent | 100% | 94 | — |
| Chivasso–Mortara Gas Pipeline | Italy | Operating | Parent | 100% | 68 | — |
| Chivasso–Poirino Gas Pipeline | Italy | Operating | Parent | 100% | 32 | — |
| Cortemaggiore–Pontremoli Gas Pipeline | Italy | Operating | Parent | 100% | 43 | — |
| Cortemaggiore–Pontremoli Gas Pipeline | Italy | Operating | Owner | 100% | 107 | — |
| | | Parent | 100% | | |
| Croatia-Slovenia Interconnector Gas Pipeline | Croatia | Proposed | Parent | — | 8 | 5.7 |
| Crotone–Maida Santa Eufemia Gas Pipeline | Italy | Operating | Parent | 100% | 98 | — |
| Enna-Bronte Gas Pipeline | Italy | Operating | Parent | 100% | 66 | — |
| Enna-Montalbano Gas Pipeline | Italy | Operating | Parent | 100% | 87 | — |
| Ferrandina–Moliterno Gas Pipeline | Italy | Operating | Parent | 100% | 83 | — |
| Flaibano-Gonars-Villesse Gas Pipeline | Italy | Operating | Parent | 100% | 47 | — |
| Foligno-Terni-Civita Castellana Gas Pipeline | Italy | Operating | Parent | 100% | 62 | — |
| Gagliano-Messina Gas Pipeline | Italy | Operating | Parent | 100% | 130 | — |
| Gallese Civita Cast–Oricola Gas Pipeline | Italy | Operating | Parent | 100% | 82 | — |
| H2Med Pipeline | Spain, France | Proposed | Parent | — | 450 | 2.72 |
| High Pressure Pipeline to West Macedonia | Greece | Under construction | Parent | 36.2% | 157 | — |
| Hoscht-St.Magrethen Gas Pipeline | Austria, Switzerland | Operating | Parent | — | 6 | — |
| Hungary-Austria Interconnector Gas Pipeline | Austria | Operating | Parent | 19.6% | 45 | 4.26 |
| Irun-Biriatou Gas Pipeline | Spain, France | Operating | Parent | — | 4 | 11.3 |
| Istrana-Caldonazzo Gas Pipeline | Italy | Operating | Parent | 100% | 110 | — |
| Istrana–Mira Gas Pipeline | Italy | Operating | Parent | 100% | 30 | — |
| Karperi–Ampelia Gas Pipeline | Greece | Operating | Parent | 36.2% | 181 | — |
| Kipi-Komotini Pipeline | Türkiye, Greece | Operating | Parent | 36.2% | 87 | — |
| Kulata-Nea Missivria Gas Pipeline | Bulgaria, Greece | Operating | Parent | — | 92 | — |
| Larrau–Villar de Arnedo Gas Pipeline | France, Spain | Operating | Parent | — | 145 | — |
| Lauria-Tarsia Gas Pipeline | Italy | Operating | Parent | 100% | 69 | — |
| Lauria–Montesano Gas Pipeline | Italy | Operating | Parent | 100% | 38 | — |
| Lindau-Daleu Gas Pipeline | Austria, Switzerland | Operating | Parent | 19.6% | 67 | — |
| Maenza-Gallese Gas Pipeline | Italy | Operating | Parent | 100% | 127 | — |
| Maenza–Melizzano Gas Pipeline | Italy | Operating | Parent | 100% | 133 | — |
| Maida Saint Eufemia-Castrovillari Gas PIpeline | Italy | Operating | Parent | 100% | 102 | — |
| Maida-Martirano Gas Pipeline | Italy | Operating | Parent | 100% | 34 | — |
| MaidaSEufemia–Reggio Calabria Gas Pipeline | Italy | Operating | Parent | 100% | 96 | — |
| Malborghetto-Camisano Gas Pipeline | Italy | Operating | Parent | 100% | 163 | — |
| Malborghetto-Flaibano Gas Pipeline | Italy | Operating | Parent | 100% | 77 | — |
| Malborghetto-Flaibano Gas Pipeline | Italy | Operating | Parent | 100% | 38 | — |
| Masera–Mortara Gas Pipeline | Italy | Operating | Parent | 100% | 125 | — |
| Matagiola-Massafra Gas Pipeline | Italy | Proposed | Parent | 100% | 40 | 3.61 |
| Mazara del Vallo-Gagliano Gas Pipeline | Italy | Operating | Parent | 100% | 224 | — |
| Mazara del Vallo-Menfi Gas Pipeline | Italy | Operating | Parent | 100% | 43 | — |
| Mazara Del Vallo-Sciacca Gas Pipeline | Italy | Operating | Parent | 100% | 50 | — |
| Megalopoli-Patras Gas Pipeline | Greece | Proposed | Parent | 36.2% | 145 | — |
| Melizzano-Castrovillari Gas Pipeline | Italy | Operating | Parent | 100% | 286 | — |
| Melizzano-Vastogirardi Gas Pipeline | Italy | Operating | Parent | 100% | 89 | — |
| Melizzano-Vastogirardi Gas Pipeline | Italy | Operating | Parent | 100% | 89 | — |
| Melizzano–Benevento Gas Pipeline | Italy | Operating | Parent | 100% | 37 | — |
| Messina–Montalbano Gas Pipeline | Italy | Operating | Parent | 100% | 77 | — |
| Methanization of Sardinia Project | Italy | Proposed | Parent | 55% | 420 | 1.68 |
| Midi-Catalonia Pipeline | Spain, France | Cancelled | Parent | — | 1,250 | 7.5 |
| Midi-Catalonia Pipeline | Spain, France | Cancelled | Parent | — | 227 | — |
| Minerbio-Castelbolognese Gas Pipeline | Italy | Operating | Parent | 100% | 44 | — |
| Minerbio-Zimella Gas Pipeline | Italy | Operating | Parent | 100% | 86 | — |
| Minerbio–Parma Gas Pipeline | Italy | Operating | Parent | 100% | 39 | — |
| Minerbio–Parma Gas Pipeline | Italy | Operating | Parent | 100% | 81 | — |
| Minerbio–Ravenna Terra Gas Pipeline | Italy | Operating | Parent | 100% | 59 | — |
| Mira–Campagna Lupia Gas Pipeline | Italy | Operating | Parent | 100% | 14 | — |
| Moliterno–Montesano Sulla Marcellana Gas Pipeline | Italy | Operating | Parent | 100% | 5.1 | — |
| Montalbano-Messina Gas Pipeline | Italy | Operating | Parent | 100% | 79 | — |
| Montalbano–Bronte Gas Pipeline | Italy | Operating | Parent | 100% | 60 | — |
| Montesano-Buccino Gas Pipeline | Italy | Operating | Parent | 100% | 57 | — |
| Morano–Tarsia Gas Pipeline | Italy | Operating | Parent | 100% | 42 | — |
| Mortara–Alessandria Gas Pipeline | Italy | Operating | Parent | 100% | 44 | — |
| Oricola–Ciciliano Gas Pipeline | Italy | Operating | Parent | 100% | 18 | — |
| Palagiano-Brindisi Gas Pipeline | Italy | Operating | Parent | 100% | 77 | — |
| Palagiano-Brindisi Gas Pipeline | Italy | Operating | Parent | 100% | 77 | — |
| Palagiano–Bernalda Gas Pipeline | Italy | Operating | Parent | 100% | 33 | — |
| Palmi–Messina Gas Pipeline | Italy | Operating | Parent | 100% | 32 | — |
| Parma-Cortemaggiore Gas Pipeline | Italy | Operating | Parent | 100% | 43 | — |
| Parma–Pontremoli Gas Pipeline | Italy | Operating | Parent | 100% | 71 | — |
| Passo Gries-Masera Gas Pipeline | Italy | Operating | Parent | 100% | 42 | — |
| Paterna-Tivissa Gas Pipeline | Spain | Operating | Parent | 19.6% | 226 | — |
| Penta-West Gas Pipeline | Austria | Operating | Parent | 19.6% | 95 | — |
| Poggio Renatico-Cortemaggiore Gas Pipeline | Italy | Operating | Parent | 100% | 139 | — |
| Poggio Renatico–Minerbio Gas Pipeline | Italy | Operating | Parent | 100% | 19 | — |
| Poirino–Alessandria Gas Pipeline | Italy | Operating | Parent | 100% | 66 | — |
| Pontremoli–La Spezia Gas Pipeline | Italy | Operating | Parent | 100% | 19 | — |
| Pontremoli–La Spezia Gas Pipeline | Italy | Operating | Owner | 100% | 43 | — |
| | | Parent | 100% | | |
| Pordenone-Istrana Gas Pipeline | Italy | Operating | Parent | 100% | 61 | — |
| Rankweil-Lienz Gas Pipeline | Austria, Switzerland | Operating | Parent | — | 8.4 | — |
| Ravenna-Recanati Gas Pipeline | Italy | Operating | Parent | 100% | 172 | — |
| Recanati–Chieti Gas Pipeline | Italy | Operating | Parent | 100% | 150 | — |
| Recanati–Foligno Gas Pipeline | Italy | Operating | Parent | 100% | 100 | — |
| Reggio Calabria–Messina Gas Pipeline | Italy | Operating | Parent | 100% | 19 | — |
| Rimini–Sansepolcro Gas Pipeline | Italy | Operating | Parent | 100% | 46 | — |
| Ripalta–Sergnano Gas Pipeline | Italy | Operating | Parent | 100% | 16 | — |
| Rogatec–Gorizia Gas Pipeline | Slovenia, Italy | Operating | Parent | — | 101 | 2.71 |
| Rognano-Mortara Gas Pipeline | Italy | Operating | Parent | 100% | 26 | — |
| Saint Stefano Di Magra-Cortemaggiore Gas Pipline | Italy | Operating | Parent | 100% | 122 | — |
| San Salvo–Biccari Gas Pipeline | Italy | Operating | Parent | 100% | 94 | — |
| San Salvo–Vastogirardi Gas Pipeline | Italy | Operating | Parent | 100% | 58 | — |
| Sansepolcro-Terranuova Gas Pipeline | Italy | Operating | Parent | 100% | 46 | — |
| Sciacca-Canicatti Gas Pipeline | Italy | Operating | Parent | 100% | 82 | — |
| Sealine Tirrenica Gas Pipeline | Italy | Cancelled | Parent | 100% | 255 | — |
| Sergnano-Mortara Gas Pipeline | Italy | Operating | Parent | 100% | 57 | — |
| Sergnano–Vigasio Gas Pipeline | Italy | Operating | Parent | 100% | 81 | — |
| Spain-Italy Offshore Interconnector | Spain, Italy | Shelved | Parent | 100% | 700 | 30 |
| TAP Interconnection Gas Pipeline | Italy | Operating | Parent | 100% | 55 | — |
| Tarsia–Crotone Gas Pipeline | Italy | Operating | Parent | 100% | 129 | — |
| Tarsia–Rende Gas Pipeline | Italy | Operating | Parent | 100% | 33 | — |
| Tarvisio-Malborghetto Gas Pipeline | Italy | Operating | Parent | 100% | 23 | — |
| Tarvisio-Zimella Gas Pipeline | Italy | Operating | Parent | 100% | 265 | — |
| Terranuova Bracciolini–Gallese Civita Cast Gas Pipeline | Italy | Operating | Parent | 100% | 169 | — |
| Terranuova Bracciolini–Livorno Gas Pipeline | Italy | Operating | Parent | 100% | 114 | — |
| Terranuova-Castelbolognese Gas Pipeline | Italy | Operating | Parent | 100% | 112 | — |
| Terranuova-Minerbio Gas Pipeline | Italy | Operating | Parent | 100% | 156 | — |
| Tesla Gas Pipeline | Türkiye, Greece, Serbia, Hungary, Austria | Cancelled | Parent | — | 1,400 | 27 |
| Thiva-Megalopoli Gas Pipeline | Greece | Operating | Parent | 36.2% | 208 | — |
| Trans-Adriatic Gas Pipeline | Türkiye, Greece, Albania, Italy | Operating | Parent | 20% | 878 | 10 |
| Trans-Austria Gas Pipeline | Austria | Operating | Parent | 87.5% | 380 | 13.7 |
| Trans-Austria Gas Pipeline | Austria | Operating | Parent | 87.5% | 380 | 13.7 |
| Trans-Austria Gas Pipeline | Austria | Operating | Parent | 87.5% | 380 | 13.7 |
| Trans-Mediterranean Gas Pipeline | Algeria, Tunisia | Operating | Parent | 50.1% | 370 | — |
| Trans-Mediterranean Gas Pipeline | Tunisia, Italy | Operating | Parent | 50.1% | 155 | — |
| Trans-Mediterranean Gas Pipeline | Italy | Operating | Parent | 50.1% | 355 | — |
| Vastogirardi-Oricola Gas Pipeline | Italy | Operating | Parent | 100% | 139 | — |
| Vastogirardi-Oricola Gas Pipeline | Italy | Operating | Parent | 100% | 139 | — |
| Veruno-Bizzarone Gas Pipeline | Italy | Operating | Parent | 100% | 48 | — |
| Vigasio–Trento Gas Pipeline | Italy | Operating | Parent | 100% | 94 | — |
| Villesse-Gorizia Gas Pipeline | Italy | Operating | Parent | 100% | 19 | — |
| West Austria Gas Pipeline | Austria | Operating | Parent | 19.6% | 245 | 10.9 |
| West Austria Gas Pipeline | Austria | Operating | Parent | 19.6% | 140 | 10.9 |
| Zeebrugge-Bacton Gas Pipeline | United Kingdom, Belgium | Operating | Parent | 24% | 235 | 25.5 |
| Zimella-Cervignano Gas Pipeline | Italy | Operating | Parent | 100% | 172 | — |
| Zimella–Istrana Gas Pipeline | Italy | Operating | Parent | 100% | 70 | — |
| Zimella–Poggio Renatico Gas Pipeline | Italy | Operating | Parent | 100% | 66 | — |